A Phylogenetic Classification of the Annoniflorae

A synoptical key to the three orders Annonales, Berberidales, and Nymphaeales of the superorder Annoniflorae is presented with discussion as to why these orders, the core of the histmical Ranales, are considered to be closely related to one another but divergent from the similarly plimitive Hamamelidales of the Hamamelidiflorae, and why the names Annonales and Berberidales are preferred to the names Magnoliales and Ranunculales. For each of the three orders detailed synoptical keys to the 33 famili es and 30 subfamilies ( 21 additional to the typical subfamilies) recognized by the author are presented . Also the included families of each order are discussed with explanation of their accepted alignment, circumscription, and geography. Finally, an extensive bibliography is listed to those publications that represent the documentation for the author's interpretation of the Annoniflorae. Five new subfamilies are published by reference to their basonyms : Mollinedioideae of the Monimiaceae, Idiospermoideae of the Calycanthaceae, Peperomioideae of the Piperaceae, and Euryaloideae and Barclayoideae of the Nymphaeaceae.


INTRODUCTION
After more than 15 years of effort toward developing a phylogenetic classification of the Angiospermae, I presented in 1968 in Aliso a naked synopsis of my classification. I published that synopsis with considerable reluctance because a classification issued without thorough documentation and explanation is only of suggestive value. However, I had hoped shortly to complete a small volume containing considerable discussion of each order and a lengthy bibliography. Other activities intervened, but now I am rewriting and expanding considerably that manuscript and adding original drawings for at least one species for each order and suborder. I plan to prepare for each order detailed synoptical keys to th e families and subfamilies currently recognized; present considerable discussion of each family explaining, where desirable, circumscription, geography, and reasons for the accepted alignment; and supply, by way of documentation, an extensive list of pertinent publications studied . Because the resulting large volume will require several years of preparation and editing before publication, I have decided to publish in various botanical journals at appropriate intervals my treatments of the various superorders or larger orders.
Piecemeal publication has certain advantages. I can expect much criticism, surely most of it constructive, from interested specialists who will want to know why I have so mistreated their favorite taxa. They will p erhaps [147] ALISO [VoL. 8,No. 2 be inspired to suggest for their special groups a more reasonable classification with appropriate exposition. Even my synopsis generated some very helpful suggestions. Such useful information from monographers will be most welcome, and will enable me in the final compilation to improve the classification, correct errors, remedy omissions, and expand discussion where the botanical audience seems to desire it. New discoveries and research and much expanded information about various angiospermous families since publication of the "Synopsis" ( Thorne, 1968) have caused me to make a number of changes in my classification. The revised synopsis will, of course, be included in the book with the much requested phylogenetic "tree," which I prefer to present as a phylogenetic "shrub," or a bit facetiously, as a phylogenetic "hedge." The principles or concepts that have guided me in the development of my classification of the Angiospermae have been published ( Thorne, 1958( Thorne, , 1963 in outline form with some discussion and examples . They have also been touched upon in two recent papers on inclusion of the Apiaceae ( Umbelliferae) in the Araliaceae ( Thorne, 1973) and the artificiality of the once widely accepted "Amentiferae" (Thorne, 1974). I have greatly expanded and modified my statement of these principles in the manuscript for my text, but only one added principle needs mention here. Like most of the others, it is a generalization so much a part of our taxonomic philosophy that it never occurred to me before to enunciate it. Briefly, the plastlcity of angiospermous organs, tissues, and cells is so pervasive that the phylogenetic value of most of their characteristics is not determinable a priori. This general plasticity, along with the prevalence of convergent evolution among the flowering plants, causes the phylogenist much pain and frustration but greatly adds to the challenge of his occupation. Each taxon requires careful study to ascertain which features are conservative and which are highly modified before we can decide which should receive the most weight in our search for the phyletic relationships of the taxon. Neither a priori nor equal weighting of characteristics is reasonable or feasible in phylogenetic studies.

SUPERORDER ANNONIFLORAE
SYNOPTICAL KEY TO OHDERS 1. Parenchymatous tissues mostly with spherical idioblasts ( essential oil cells ); mostly woody terrestrial plants with relatively unspecialized xylem ( some taxa primitively lacking vessels); stomata commonly paracytic; pollen grains mostly anasulcate ( distally aperturate) or phyletically closely derived types -----------·---ANNONALES l'. Parenchymatous tissues lacking spherical idioblasts; mostly herbaceous or soft-woody terrestri al plants with relatively specialized xylem or rhizomatous aquatic herbs; stomata commonly anomocytic; pollen grains various . 2. Plants mostly terrestrial herbs, soft-woody climbers or shrubs, or rarely trees; lacking cordate or peltate floating leaves; stomata mostly on tl1e lower surface of leaves; cambium and relatively specialized vessels present; pollen grain never anasulcate but commonly tiicolp ( oroid )ate or phyletically closely derived types ---------··---------------------------------·-----------------BERBERIDALES 2'. Plants all aquatic herbs, mostly rhizomatous; leaves mostly cordate to peltate, floating or emersed ( or submersed and very thin or much dissected ); stomata on the upper surface of leaves; vascular bundles monocotyledonoid and mostly scattered , lacking cambium, and with vessels absent or tracheidlike; pollen grains mostly anasulcate or closely deiived types ( tricolpate only in Nelumbo) ____ NYMPHAEALES DISCUSSION OF ANNONIFLORAE At the Tenth International Botanical Congress in Edinburgh I presented a realignment ( Thorne, 1964) of the traditional Ranales in which I split this partly unnatural assemblage of plants retaining numerous primitive angiospermous characteristics into three superorders, Annoniflorae, Nymphaeiflorae, and Hamamelidiflorae. The last group really does not concern us here and needs but brief mention. Often treated in the Ranales, Trochodendron Sieb. & Zucc., Tetracentron Oliv., Euptelea Sieb. & Zucc., and Cercidiphyllum Sieb. & Zucc. ( which form monogeneric families in my Trochodendrineae of the Hamamelidales, Hamamelidiflorae) are ancient relicts once widely distributed in the Northern Hemisphere but now restricted to the humid forests of eastern warm-temperate Asia. Like the Annoniflorae these living fossils retain many primitive features in their stern anatomy, both Trochodendron and Tetracentron being primitively vesselless, but their flowers, pollen, and other organs appear to be more specialized. Although trees like many Annonales, they lack the spherical idioblasts containing essential oils and the monosulcate or closely derived pollen grains characteristic of that order. Instead, they approach rather closely Eucommia Oliv., Platanus L., and the Hamamelidaceae in their stem anatomy, floral morphology, pollen, fruit, often winged seeds, leaf anatomy, embryology, past and present geography, and geological history. They are best treated as four suborders in the Hamamelidales. The Hamamelidiflorae presumably had distant common ancestry with the Annoniflorae but the two groups appear to have diverged rather widely from one another by late Cretaceous time. I will treat the Hamamelidiflorae in much more detail at a later date.
Further sh1dy of the Nymphaeales, especially of the serological data assembled by my former colleague J.-P. Simon ( 1970Simon ( , 1971, has caused me to delete the superordinal name N yrnphaeiflorae and to place the Nymphaeales with the Annonales and Berberidales in the Annoniflorae. Thus the traditional Ranales ( sensu lato) are narrowed down to one superorder.
I have often been asked why I use the names Annonales and Berberidales instead of the currently more popular Magnoliales and Ranunculales. Although observation of priority is not required by the International Code of Botan-ical Nomenclature ( Stafleu, 1972) for names above rank of family, I prefer to apply the principle of priority throughout my classification.
12. Flowers unisexual, apetalous; filaments united in solid column with anthers free or laterally concrescent; carpel solita1y with single basal ovule; fruit fleshy to subwoody, dehiscent; seeds arillate; endosperm usually ruminate, starchy; chromosome numbers, n = 18, 21, 25; rain-forest trees of all main tropical areas _________ _   , and epizoochorous dispersal ------------------------------ Habit arboreal; leaf trace l ; stamens laminar with long, narrow, dorsal, extrorse microsporangia; gynoecium of 1 or 2 carpels with broad, fleshy, papillose, almost sessile stigma; cotyledons 4 or 3, massive, fl eshy, subsessile, peltate in large seed 4-5 cm long; xylem diffuse-porous ; vessel elements with multiple scalariforrn perforations; parenchyma abundant; rays high with mostly procwnbent cells ; vasicentric tracheids absent ; endemic rain-forest monotype of NE Queensland  Flowers hypogynous ( epigynous only in H ypodaphnis ), usually small, bisexual, less commonly unisexual; tepals basically trimerous, usually in 2 whorls, free or outer gamosepalous; 4-or 2-localar stamens and staminodia typically in 4 whorls, at least 1 whorl having sessile or stalked , paired glands associated with each filament ; usually 2 outer whorls of anthers dehiscing introrsely and inner third whorl extrorsely ; fruits drupaceous or baccate, often subtended by cuplike calyx; trees or shrubs ( except for the parasitic vines of Cassytha ); leaves alternate, rarely . Flowers epigynous, bisexual or commonly unisexual; 5-to 3-merous; 10-3 tepals in l or 2 whorls; stamens equal to or fewer in number than outer whorl of tepals; anthers dehiscing laterally or introrsely by 2 valves; fruits dry, indehiscent, ribbed nuts, sometimes winged; trees, sh1ubs, or lianas; chromosome numbers, n = 15, 20 The Annonales are a large, diverse aggregation of mostly relict families surviving in the moist, warm forests of the tropical and warm-temperate zones. They retain in common many more unspecialized, i.e., primitive and probably ancestral angiospermous, characteristics of stem, foliage, flowers , pollen, ovules, fruit, and seeds than any other angiospem1ous order, including the relatively unspecialized Berberidales, Nymphaeales, Hamamelidales, Rosales, and Liliales . Among these more primitive feahu-es, as currently accepted, and retained in varying degree by different members of the order, are: habit arboreal or shrubby; leaves simple, alternate, pinnate veined, entire, petiolate, glabrous, evergreen, exstipulate, with paracytic stomata, and often with two leaf traces from a single leaf gap; cambium initials very long and fusiform with overlapping ends; wood anatomy very unspecialized ( vessels absent altogether or tracheidlike with vessel elements characterized by great length, small diameter, tl1in walls, angular crosssectional appearance, very oblique end walls, scalariform perforation plates with numerous fine bars, scalariform intervascular pitting, diffuse and solitary vessel arrangement; tracheids medium to moderately long with conspicuous bordered pits; wood parenchyma diffuse; rays of primitive heterogeneous type with numerous uniseriates) ; flowers mostly bisexual, actinomorphic, with perianth parts often poorly differentiated, and floral parts generally indefinite in number, distinct from one another, and spirally arranged on a convex receptacle; stamens rather broad and unmodified into filament, anther, and connective; pollen grains anasulcate ( distally mono-aperh1rate) or of closely derived types; carpels styleless with broad, involute or conduplicate lamina bearing an indefinite number of anatropous, marginal ovules, margins stigmatic over a large area or with stigmatic hairs abundant I and each family display different trends toward specialization, fusion, amplification, or reduction. None of the families is, therefore, to be derived from any other annonalean family. All represent different surviving lineages from common but long-extinct protoannonalean stock. Various families of other orders, especially the related Berberidales and Nymphaeales, retain many unspecialized features also. However, the members of the Annonales are distinguished from plants of these other orders definitively by the possession in their parenchymatous tissues of characteristic spherical secretory cells ( Fig. le) , containing essential, or "ethereal" oils or resinous contents. The evolutionary significance of these cells is not understood, but their presence is diagnostic for members of the order. Among dicotyledons only the Nymphaeales also have members with anasulcate or closely derived disulcate, polycolpoidate, or inaperhuate pollen grains ( Erdtman, 1952) , and nymphaealean species lack the spherical essential oil cells.
The 23 families and perhaps 9,500 species of this diverse but natural assemblage have been divided into several orders by recent phylogenists such as Hutchinson ( 1964Hutchinson ( , 1973 , Takhtajan ( 1969), and Smith ( 1972), mostly because of the several divergent evolutionary pathways followed by different groups of families. I believe that subdivision of the Annonales into several suborders serves the purpose of calling attention to these different evolutionary lines, while retaining them in one order indicates their close affinity and obviously close common ancestry. SUBORDER WINTERINEAE WrNTERACEAE Lindley 1830.-Just as the Annonales share more primitive features than any other dicotyledonous order, so within this order the single family Winteraceae, comprising the suborder Winterineae, retains the largest number of primitive characteristics in the vegetative and reproductive structures of its members . The six currently accepted genera (Bubbia v. Tiegh., Drimys J. R. & G. Forst., Belliolum v. Tiegh., Pseudowintera Dandy, Tasmannia R. Br., and Zygogynum Baill.) contain more than 100 species of small trees or shrubs found mostly in areas fringing   ( Smith, 1943) and another to Madagascar ( Capuron, 1963) . Among the most distinctive features of the Winteraceae are the entirely vesselless wood ( Fig. 1 i-1 ), the stomata occluded by waxy deposits, and the pollen in permanent tetrahedral tetrads, each grain with a distal germination pore ( Fig. lm ). Especially primitive, in addition to the vesselless xylem, are the long cambial initials and tracheids ( Fig. li), heterogeneous rays; multiseriate ( occasionally scalariform) bordered tracheary pitting ( Fig. li) ; diffuse to tangentially banded wood parenchyma; mesogeneous paracytic stomata! apparatus ( with one or more subsidiary cells parallel to the stoma) in the alternate, entire, pinnae-veined, exstipulate, evergreen leaves; intercalary (  ( Bailey, 1944;Bailey andNast, 1943-1945;Nast, 1944;Smith, 1943a,b ;Swamy, 1952;Vink, 1970).
The various genera of Winteraceae display many trends of morphological specialization leading to dwarfing of shrubs and leaves; simple, terminal flowers; calyptrate calices; few or no petals; functional unisexuality; differentiated and few stamens; reduced number of carpels ( to one) with closure of the megasporophyll and restriction of the stigmatic crests to a subapical projection ( Fig. lb ); and syncarpy. SUBORDER ILLICIINEAE lLLICIACEAE A. C. Smith 1947 and ScmsANDRACEAE Blume 1830-The two families of the Illiciineae, Illiciaceae and Schisandraceae, both basically southeastern Asiatic with meager representation in southeastern North America, are more closely related to the Winterineae than to any other group of Annonales. Besides the usual spherical secretory cells in the parenchymatous tissues, and the paracytic stomatal apparatus, Illicium L. ( Fig. 2) especially resembles the Winteraceae in its small tree or shrubby habit, alternate, exstipulate, evergreen leaves ( Fig. 2a), and primitive features of its wood. It does possess primitive vessels, but the vessel elements are tracheidlike: long, slender, thin-walled, angular with greatly overlapping end walls with numerous bars in the scalariform perforation plates, with intervascular pitting scalariform or transitional, and diffusely scattered throughout the xylem. The imperforate tracheary elements are thick-walled tracheids with conspicuous bordered pits. The xylem parenchyma is scanty diffuse and abaxial paratracheal, and the rays are multiseriate. Although the flowers differ considerably from those of the Winter-e Fig. 2. Illicium floridanu,m Ellis, Illiciaceae, southeastern United States, 1·epresenting the Illiciineae.-a. Fruiting branch bearing evergreen, alternate leaves and single follicetum of one-seeded ventrally-dehiscent follicles in whorl, X 0.4.-b. Single flower consisting of undifferentiated perianth of many purplish red tepals, stamens similarly numerous and many-seriate, and single whorl of separate carpels, X 0.8.-c. Floral axis with all parts removed except two carpels in longisection to show in each single, basally attached ovule, X 3.-d. Developing young fruit, X 1.5.-e. Stamens showing introrse dehiscence by longitudinal slits, X 1.7.-f. Apparentl y syncolpoidate pollen grain, ca. 28 µ.-g. Two glossy, flattened seeds in lateral view, X 2.7, and one from hilum view, X 4. ALISO [VoL. 8,No. 2 aceae, the free carpels ( Fig. 2b,c) are basically conduplicate, with the stigmatic crests produced into a pseudostyle or a vascularized style stigmatic along all or much of its length or along the upper side ( Bailey and Nast, 1948;Smith, 1947). In both Illicium and the Schisandraceae the chromosome numbers are n=l4 or 13 (Raven and Kyhos, 1965;Raven, 1974). Nonetheless, the differences between the Winteraceae, Illiciaceae, and Schisandraceae suggest the segregation of the two groups into separate suborders. Among the more striking differences of the Illiciineae from the Winterineae are the xylem vessels, the unilacunar as opposed to trilacunar nodes, the pseudosiphonostelic arrangement of the prin1ary vascular tissues in Illicium, the nonoccluded stomata with intercellular intrusions of the cuticle, apparently 3-or 6-colpate pollen grains released separately ( Fig.  2f) , reduced number of ovules in the carpels (Fig. 2a,c), and fundamental differences in the flowers and floral parts.
Although the lianous, unisexual-flowered, baccate-fruited species of Schisandraceae are considerably more specialized than members of the Illiciaceae, the two families are closely linked by their unilacunar nodes, elongated or cambiform "mucilage" cells in the phloem, similar stomata, cuticles, pollen, and chromosomes ( Bailey and Nast, 1948;Wood, 1958). The Illiciaceae consist of the single genus Illicium ( Fig. 2) with perhaps 37 species of evergreen-leaved shrubs or small trees in southeastern Asia from Japan south to India and Borneo and two to four species in the southeastern United States, Mexico, and the Greater Antilles. The Schisandraceae are monoecious or dioecious climbing shrubs or twining woody vines with coriaceous or often thinner, toothed leaves. The perhaps 47 species are divided nearly equally between the two genera Schisandra Michx. and Kadsura Juss., restricted to southeastern Asia from Japan and Korea to Ceylon and Java except for the single species, Schisandra glabra (Brickell) Rehder of the southeastern United States ( North Carolina to eastern Louisiana and Arkansas).
Also in the Annonineae, five of the families show strikingly similar characteristics in the young stem: superficial origin of periderm, sclerified pith diaphragms, stratification of the secondary phloem into tiers of hard and soft b as t, V-shaped rays in the phloem, cortical sclereids, and a eustelic vascular cylinder with each bundle capped by thick-walled fibers (Bailey, Nast, and Smith, 1943;Canright, 1955;Vander Wyk and Canright, 1956 ). Four of the families have crystalliferous parenchyma in the cortex and pith. All five families share many features in the mature wood as well, with similar vessel distribution, apotracheal b anded wood parenchyma, and similarities in the rays. Of intermediate sp ecialization in their wood are Degeneria and tropical genera of the Magnoliaceae; somewhat transitional are the Myristicaceae and temperate members of the Magnoliaceae; and relatively more specialized are the sp ecies of Galbulimima ( Himantandraceae) and the Annonaceae ( Vander Wyk and Canright, 1956 ) . Eupomatia and the Canellaceae lack some of the above-listed features, especially the pith diaphragms of sclereids and stratification of the phloem. Furthermore, their wood is exceedingly primitive, with long, narrow vessel elements with long tapering end walls containing scalariform perforation plates with many ( to 150 ) bars and with scalariform to opposite intervascular pitting; apotracheal diffuse to sparingly paratracheal wood p arenchyma; and narrow, high, heterogeneous rays. In other features, however, of nodal anatomy, foliage, flowers, seeds, etc., Eupomatia displays its relatively close relationship to Galbulimima and Degeneria and the Canellaceae to the Annonaceae and M yristicaceae.
Because members of the Annonineae are relatively well known to north temperate botanists, their primitiveness as compared with that of species of the Winteraceae and Illiciaceae has perhaps been somewhat overplayed. Nevertheless, in comparison with most other families _ found in the north temp erate zone, plants of th e Am10nineae are indeed well endowed with unspecialized characteristics. The phyllomelike stamens of Degeneria, Galbulimima, and some species of Magnoliaceae, with their embedded, median, elongate microsporangia have been considered by some morphologists as the most primitive among livin g angiosperms ( Canright, 1952 ) . Though the primitive stamens probably were relatively undifferentiated, much as those in some Winteraceae, the primitive microsporangia were probably marginal and protuberant. The laminar stamens with embedded microsporangia may well be a specialization protecting the pollen from the chewing mouthparts of beetles and other crawling insects much as closed carpels guard the ovules. The somewhat laminar type of placentation described for some of these taxa, like those in Degeneria and Eupomatia, may also be a modification from marginal placentation removing the ovules from too close proximity to the open, stigmatic margins of the apparently conduplicate carpels. Though retaining many very primitive feahires, members of th e Annonineae also show considerable sp ecialization beyond ALISO [VoL. 8,No. 2 that found in species of the Winteraceae and Illiciaceae, especially in their nodal and stem anatomy and in their flowers.
MAGNOLIACEAE A. L. Jussieu 1789.-The relatively well-known Magnoliaceae consist of 12 genera and 210 to 230 species ( Dandy in Hutchinson, 1964). Although in the Tertiary they were widely distributed in the Northern H emisphere, today all the genera are entirely or mostly restricted to eastern Asia from Japan and Manchuria to New Guinea and India, with three genera also represented in North Ehrendmfer, Krendl, Habeler, and Sauer, 1968;Sauer and Ehrendorfer, 1970;Raven, Kyhos, and Cave, 1971;and Raven, 1974 ) .
ANNONACEAE A. L. Jussieu 1789.-The Annonaceae are a rather large family with perhaps 130 genera and 2,300 species (Walker, 1971). Except for the temperate American pawpaw genera Asimina Adans. ( Fig. 3) and Deeringothamnus Small, the family is tropical witl1 good representation in all four inajor sectors of the tropics. Unlike the preceding families, the Annonaceae seem to have their more primitive members not in Asia or Australasia but in tropical America and Africa ( Walker, 1971( Walker, , 1972 , as with the closely related Myristicaceae and Canellaceae, possibly stemming from ALISO [VoL. 8,No. 2 those Cretaceous times when Africa and South America were presumed to form West Gondwanaland. Of all living angiosperm families, at least, these seem to be the most likely survivors of such possible continental rifting and rafting. One genus, Annona L., is restricted to tropical America, including southern Florida, and tropical Africa, but this distribution, especially that of A. glabra L ., very likely is a product of relatively recent long-distance dispersal by water currents. The shrubs and small trees of the Annonaceae are rather easy to recognize from their often nodding, maroon, white, or yellowish flowers with trimerous perianth in three whorls ( Fig. 3b,d ); numerous, spirally arranged "peltate" stamens ( Fig. 3c,g) and separate carpels ( Fig. 3c,e) ; usually baccate ( Fig. 3a) or syncarpous ( rarely follicular) fruits; and seeds with ruminate endosperm ( Fig. 3j). However, such specializations as unisexual flowers, reduced number of petals, few and whorled stamens, carpels reduced to one or fused into a compound, uniloculate pistil, and arillate or winged seeds can complicate recognition. MYRISTICACEAE R. Brown 1810.-The Myristicaceae are a strictly tropical family best known for the once valuable spices nutmeg and mace from the seed and aril of Myristica fragrans Routt., a native of the Moluccas, or Spice Islands. With about 15 genera and 250 species ( Buchheim in Melchior, 1964) the majority of genera occur in Africa ( 5) , Madagascar ( 1) , and tropical America ( 5); whereas, the vast majority of species ( 213) belong to the four Asiatic genera that range from southern China to Australia, Polynesia, and Ceylon. In America Compsoneura Warb. and Virola Aubl. range north to Mexico or the West Indies (Smith and Wodehouse, 1938). Members of the family can be recognized as rain-forest trees with small, apetalous, impe1fect, cyclic flowers with synsepalous calyx, stamina! column or single carpel with single basal ovule, and baccate to subwoody fruit usually dehiscing to show the single, usually ruminate seed with lacerate aril. The close similarity of the protein-accumulating sievetube plastids of Myristicaceae with those of the Annonaceae, Canellaceae, and Aristolochiaceae has been pointed out by Behnke ( 1971) . CANELLACEAE C. F . P. Martius 1832.-The six genera and 21 species ( Occhioni, 1948;Wilson, 1960) of the small family Canellaceae are restricted to the tropical forests of America, eastern Africa ( W arburgia Engl.), and Madagascar ( Cinnamosma Baill.) ( Thorne, 1973c). Cinnamodendron Engl., Pleodendron v. Tiegh ., and Canella P. Br. occur in the West Indies, and Canella winterana ( L.) Gaertn. reaches north to the Florida Keys and Cape Sable at the south end of the Florida peninsula. Capsicodendron Hoehne is endemic in southern Brazil. Despite the gynoeciurn of two to six syncarpous carpels forn1ing a rnonoloculate ovary with two to six parietal placentae ( as in two genera of Annonaceae), members of this family are readily placed in the Am1onales by their spherical secretory oil cells, anacolpate pollen grains, and exceedingly primitive stern anatomy. The monodelphous stamens, embryology and occasional ruminate seeds, pollen grains, P-type sieve-tube plastids, wood anatomy, and other for the whole order Annonales ( Raven and Kyhos, 1965;Ehrendorfer, Krendl, Habeler, and Sauer, 1968;Raven, Kyhos, and Cave, 1971;Walker, 1972;and Raven, 1974).
SUBORDER ARISTOLOCHIINEAE AmsTOLOCHIACEAE A. L. Jussieu 1789.-The Aristolochiaceae are a moderatesized family of at least seven genera and perhaps 600 species ( Melchior, 1964), widely distributed in the tropics and warm temperate areas, and consisting mostly of shrubs, lianas, or perennial herbs. Aristolochia L. and Asarum L. ( Fig. 4) are represented in Europe and Asia and in both eastern and western North America, the latter as far north as Quebec. Because the largest and best-known genus Aristolochia, with up to 500 species, has often huge and bizarre flowers ( Hoehne, 1942), always apetalous, with a highly specialized, gamosepalous, usually bilaterally symmetrical, petaloid calyx, stamens adnate to the style to form a gynostemium, inferior, syncarpous ovary, and lianous habit with expectedly specialized stem anatomy, the family has rarely been included in the Annonales ( but see Wettstein, 1935). Often the family is treated as a separate order ( Cronquist, 1968;Takhtajan, 1966Takhtajan, , 1969 or allied with such improbable relatives as the parasitic Rafflesiaceae and Hydnoraceae and the tropical Nepenthaceae ( Melchior, 1964;Hutchinson, 1973). Nonetheless, the various well-known genera of the Aristolochiaceae retain enough primitive characteristics to serve quite adequately as clues to the annonalean relationships of the family. Throughout the family, and, for example, in the western American Asarum caudatum Lindl. ( Fig. 4), one can observe such features as the spherical secretory oil cells; simple, entire, exstipulate, alternate leaves ( Fig. 4a); trimerous bisexual flowers ( Fig. 4b,c); stamens with prolonged connective ( Fig. 4b, c, e) ; inaperturate pollen grains ( Fig. 4f) ; and seeds with rudimentary embryo embedded in abundant endosperm ( Fig. 4g). For those requiring more evidence, there is even a nonmissing link, Saruma henryi Oliv., a relict monotype from Hupeh, China, which offers definitive evidence. It is a perennial caulescent herb with radially symmehical flowers ( see drawing in Oliver, 1889;or Thorne, 1963), with three conspicuous, reniform, separate petals, as well as three green sepals, six essentially separate, semi-superior carpels, anasulcate pollen grains, and follicular fruit, along with the other primitive features listed above for all members of the family.
That food preferences of insect larvae indicate biochemical affinities of a family is shown vividly in the Aristolochiaceae by the swallowtail butterflies of the Papilioninae ( Munroe, 1953). The larvae of members of the tribe Troidini feed primarily upon foliage of species of Aristolochiaceae.
The larvae of the other two tribes, Graphiini and Papilionini, feed mostly on Annonaceae, Canellaceae, Hernandiaceae, Lauraceae, Magnoliaceae, Monimiaceae, Piperaceae, and Winteraceae of the Annonales, as well as on the chemically related Rutaceae of the Rutales, and scattered members of other, unrelated families ( Ehrlich and Raven, 1964). The competence of these pragmatic chemists is attested to by the publications of Hegnauer ( 1960b, 1964) and others, who have discussed the biochemical similarities of the family to the other Annonales. The basic chromosome number for the Aristolochiaceae seems to be x = 7, "with aneuploid reduction at either the diploid or tetraploid level to produce x = 13" ( Raven, 197 4).

SUBORDER LAURINEAE
Forming another apparently nahiral assemblage among the Annonales is the large group of ten families with unilacunar nodes, the nodal type considered as probably the most primitive among the flowering plants ( Bailey, 1965;Fahn and Bailey, 1957) . As with other suborders of the Annonales the members of the Laurineae show their relationship to one another as much by common b.-ends of specialization in all their parts as by their rather sporadic retention of ancestral, primitive features. Aside from the nearly ubiquitous spherical secretory cells, some of the more primitive features retained by the Laurineae are : primitively vesselless xylem ( only Amborella Baill. and Sarcanclra Gardn.) and other commonly associated unspecialized xylem and phloem characteristics; bracteoles and tepals of the flowers often numerous, spirally arranged, and little differentiated; stamens and carpels similarly spirally arranged and little specialized; pollen grains anacolpate and numerous; ovules anatropous and developing into seeds with abundant endosperm and small undifferentiated embryo.
More striking similarities among the Laurineae are some relatively specialized conditions found in many of the families. Plants of most of the families have leaves that are opposite and exstipulate, exceptions being the rather primitive monotypes Amborella trichopoda Baill. and Lactoris fernandeziana Phil. and most species of the much more specialized Lauraceae and Hernandiaceae. Stamens with paired staminodial or glandular appendages and anthers opening by flaplike valves are unusual and often associated specializations commonly found in the Monimiaceae, Gomortegaceae, Lauraceae, and Hernandiaceae. Another common evolutionary tendency is the development of a cup-shaped floral receptacle, as found in various subfamilies of the Monimiaceae and Calycanthaceae. The ALISO [VoL. 8,No. 2 Calycanthaceae, Lauraceae, and Hernandiaceae have specialized seeds in which the cotyledons are so well developed before germination that the cotyledons have taken over food storage from the endosperm. Gomortega keule (Molina) Johnst. also has a well-developed embryo but retains much endosperm. Other evolutionary tendencies common in the suborder include the usual specializations of the stem tissues; modification of the basic two leaf traces to three or more or to a single arc-shaped trace; attainment of a definite number of parts in whorls in the flower ; both connation and adnation in the flower leading to gamosepaly, syncarpy, and epigyny; specializations of the stamens and carpels; extreme reduction in the flowers, including loss of perianth, reduction of stamens, carpels, and ovules to one of each or even to the unisexual condition. The pollen grains have commonly evolved from the anasulcate to the acolpate, dicolpate, polycolpate, or even polyporate conditions. The basic follicle has mostly given way to the single-seeded, indehiscent berry, drupe, or nutlet. Finally, the arborescent habit has been replaced in several families by small shrubs, lianas, suffruticose herbs, and even, in Cassytha L., to slender, twining, parasitic vines.
AMBORELLACEAE Pichon 1948.-Showing the most remarkable assortment of retained ancestral and derived specialized features is the shrubby Amborela trichovoda of New Caledonia, the home of numerous other equally fascinating relicts. The wood is without vessels and the other stem features are very primitive, the nodes are unilacunar, and the leaves are alternate, exstipulate, glabrous, and evergreen. The vascular strand from the node, however, is a single arc-shaped leaf trace and the leaves have an undulate margin. The Winteraceae-like stamens are relatively undifferentiated, and the separate carpels, sealed below, retain conduplicate stigmatic crests above; yet the species is dioecious with no carpellodia in the male and only one or two staminodia in the female flowers. The pollen grains appear to be transitional from monoaperturate to acolpate; and the one-seeded, indehiscent fruit is stipitate, reticulate-pitted, and <lrupaceous ( Bailey, 1957;Bailey and Swamy, 1948). AusTROBAILEYACEAE Croizat 1943.-With primitive vessels, otherwise unspecialized stem features, and two vascular strands from the nodes, the two species of Austrobaileya C. T. White of northeastern Queensland are scandent shrubs to high-climbing lianas with opposite leaves. Sparsely supplied with companion cells, the sieve tube elements were formerly believed to be exclusively sieve cells until studied by Carlquist ( pers. commun.) and others. Its bisexual flowers with numerous, spirally arranged, undifferentiated tepals, laminar stamens, anasulcate pollen grains, carpels with unsealed, conduplicate styles, and relatively numerous marginal ovules, are considerably more primitive than those of any other members of the Laurineae ( Croizat, 1940;Bailey and Swamy, 1949;Srivastava, 1970). TRIMENIACEAE Gibbs 1917.-Also restricted to the southern Pacific area are the eight small trees or lianas of the two genera Trimenia Seem. of New Guinea to Polynesia and Piptocalyx Oliv. ex Beuth. of New South Wales and New Guinea. As with Amborella and Austrobaileya, the exclusion of these genera from the Monimiaceae seems fully justified. Though they possess primitive internal stem characteristics, nodal anatomy, and decussate leaves, the two genera of the Trimeniaceae differ from the Monimiaceae by the absence of hippocrepiform (horseshoe-shaped) sclereids, of any fusion in the floral parts, of any tendency toward a concave receptacle, and by the presence of mucilage cells ( as in the Lauraceae) , of intergrading, decussate bracteoles and tepals, and of the capitate, brushlike stigma ( Money, Bailey, and Swamy, 1950;Rodenburg, 1971 demoy, 1863;Thierry, 1912;Swamy and Bailey, 1950;Swamy, 1953a, b, c;Vijayaraghavan, 1964;and Endress, 1971). & Prantl 1888.-The monotype Lactoris fernandeziana, a relict and nearly extinct, rather succulent small shrub of Masatierra of the Juan Fernandez Islands, has with even less reason sometimes also been placed with the Piperineae. Presumably the much reduced size of tl1e plant, the alternate, stipulate leaves from swollen nodes, and the small apetalous flowers have led to that treatment. However, the unilacunar nodes with two vascular strands; the relatively specialized xylem; the trimerous flowers usually with three tepals, six stamens in two whorls, and three separate carpels connate only at the base; pollen grains in permanent tetrads; carpels with six to eight marginal ovules; follicular fruit; and seeds with no perisperm, abundant endosperm, and undif- ALISO [VoL. 8,No. 2 ferentiated embryo ( Carlquist, 1964) , all argue against any close relationship with the Piperineae. These same characteristics, and others, do argue strongly, however, for inclusion of this species in the Laurineae, probably closest to the Chloranthaceae and Monimiaceae, which are rather more specialized in some reproductive features.

LACTORIDACEAE Engler in Engler
MoNIMIACEAE A. L. Jussieu 1809.-The great diversity of the probably very old family Monimiaceae has invited many attempts at dissolution of the family, the latest efforts by Schodde ( 1969Schodde ( , 1970 and Smith ( 1972) . In their very important treatment Money, Bailey, and Swamy ( 1950) removed from the family those taxa that were really extraneous there, as Amborella, Austrobaileya, and the Trimeniaceae. Although there are at least five, and probably several other, major evolutiona1y lines that have diverged from now extinct common ancestors, the rather large complex of retained primtive features, combined with common evolutionary tendencies, suggests to me parallel treatment of these diverse lineages as subfamilies in one variable family. The logical alternative treatment would be to erect five or more separate and obviously closely related families , an exercise in taxonomic inflation that would seem to serve no useful purpose. Among the features that tie the subfamilies together are the woody habit with decussate, exstipulate, often serrate leaves ; hippocrepiform sclereids usually present in the pericycle region of the stem; receptacle usually slightly to deeply concave, cupulifonn, or urceolate; basically decussate tepals; usually numerous and separate carpels and stamens; solitary anatropous ovule; and fruits indehiscent drupelets or nutlets. Common tendencies toward more specialized xylem; unisexual flowers ; stamens with associated pairs of appendages and anthers opening by flaplike valves; and pollen grains acolpate, dicolpate, or other closely derived types from the anasulcate condition, are displayed in various of the subfamilies ( Perkins, 1911;Garratt, 1934;Money, Bailey, and Swamy, 1950;Verdcourt, 1968;Sampson, 1969;andSchodde, 1969, 1970). Because the subfamilies of the Monimiaceae are treated in some detail in the synoptical key to families and subfamilies of the Annonales above, they need little further consideration here. One or two comments, however, may be in order. A new subfamily Peumoideae was published by Schodde ( 1970) for Peumus boldus Molina of Chile, formerly included in the Monimioideae. Peumus is indeed rather divergent from the rest of the Monimioideae, but so also in many of the same characteristics are the species of M onimia Thou. Because the two genera seem to belong together in a separate subfamily, that subfamily must be called the Monimioideae rather than the Peumoideae because it contains the type genus of the family. The remaining genera that were formerly associated with the two genera must receive a new subfamily name, Mollinedioideae sta. nov.
Glossocalyx Benth., with three dioecious species in tropical West Africa, has primitive vessel elements, scanty parenchyma, septate fibers , anisophyllous leaves, and an oblique, cyathiform calyx. These features are certainly widely divergent from those in the American members of the Siparunoideae. A thorough study of the subfamily probably would result in placing the African and American taxa in separate tribes if not separate subfamilies.
The Monimiaceae are a moderate-sized family of more than 30 genera and perhaps 350 species ( Hutchinson, 1964). It is primarily a family of the h·opics and the temperate regions of the Southern Hemisphere. It is especially well developed in the Asiatic, Malesian, and American h·opics, in Australasia, and on the islands in the Indian Ocean, including Madagascar. Except for Glossocalyx and Xymalos Baill., the family is unrepresented in mainland Africa; and only Peumus boldus and Laurelia aromatica Juss. are found in temperate South America. The tropical American genera Mollinedia Ruiz & Pav. and Siparuna Aubl. range north into Mexico. Probably the most in1portant members of the family from the phylogenetic point of view are the two species of the genus Hortonia \Vight ex Arn. and subfamily Hortonioideae, endemic in Ceylon. Certainly they retain the largest constellation of primitive vegetative and reproductive features in the family. Smith has recently ( 1972) elevated the genus to family status. GoMORTEGACEAE Reiche 1896.-Rather closely related to the Monirniaceae is Gomortega keule , the sole member of the Gomortegaceae, a small tree endemic to the area around Concepcion, Chile. It agrees with the former family in its primitive xylem features; unilacunar node; decussate, exstipulate leaves; undifferentiated tepals; separate, spirally arranged stamens with anthers opening by valves; inner stamens with paired glands; pendulous, anatropous ovules; and drupaceous fruits. On the other hand, it is amply distinct from the Monimiaceae in its syncarpous, two-or three-carpellate and -loculate, epigynous ovary with one ovule in each locule; the welldeveloped, large embryo; and the two leaf traces from the nodes (Reiche, 1896;Stern, 1955).
Calycanthus australiensis Diels, a rain-forest tree of northeastern Queensland, has recently been rediscovered and redescribed as Idiospermum australiense ( Diels) S. T. Blake ( 1972 On the other hand, tropical rain-forest trees tend to preserve more primitive, diffuse-porous xylem and evergreen leaves. Also to compete with other seedlings under heavily shaded, rain-forest conditions, large seeds with fleshy, massive cotyledons, sometimes three or four in number ( cf. Degeneria), are common. In maturing such large-seeded fruits from individual carpels, a reduction in number of carpels in a flower is also predictable. However, the differences in habit, leaf traces, more primitive stamens, reduced number of carpels, sessile stigma, cotyledons, and xylem anatomy do seem to add up to subfamily status for Idiospermum. The flowers of the Calycanthaceae are known generally to be pollinated by beetles ( Diels, 1916;Grant, 1950). Taking a still different evolutionary pathway from their common ancestry with the Monimiaceae are the members of the large, mostly tropical family Lauraceae, and the much smaller, wholly tropical family Hernandiaceae.
In both families there have evolved basically cymose, cyclic flowers with a definite number of perianth parts and sporophylls; several whorls of stamens with anthers dehiscing by valves; spinulose, acolpate pollen grains; a solitary carpel with single, apical, pendulous ovule; and single seed with a large embryo absorbing all the endosperm by maturity. Unlike members of tl1e Monimiaceae, the species of these two families have retained primarily alternate leaves. LAURACEAE A. L. Jussieu 1789.-The Lauraceae consist of 31 genera and between 2,000 and 2,500 species ( Kostermans, 1957). They are primarily small to moderate-sized trees of tl1e lowland to montane rain forests, though occasionally also among the canopy species. They are especially abundant in tropical America and southeastern Asia east to Malesia and eastern Australia and south to Madagascar. They are poorly represented in mainland Africa, and relatively few in species in temperate forests. Among the genera reaching temperate areas are Lindera Thunb., Litsea Lamk., Persea Boehm., and Sassafras Bercht. & Presl in eastern America and eastern Asia, and Umbellularia Nutt in western America. In the Canary and Madeira Islands off northwestern Africa in the relict laurel forests are Apollonias ~ carpels enclosed in flask-shaped hollow of pubescent cup-shaped receptacle but with filiform styles exserted, and some of the numerous stamens inserted on receptacle, X 2.-d. Stamens, each terminated by succulent food body on connective, X 11.-e. Ovoid, conspicuously veined, indehiscent pseudocarp from accrescent receptacle, X 0.7. ' . d f Fig. 6. Anemopsis californica Hook., Saururaceae, western North America, representing the Piperineae.-a. Flowering perennial herb with one leafy stolon, mostly basal leaves, and two flowering stems terminated by Anemone-like conical spike subtended by involucre of white, often reddish-maculate bracts, each of the small flowers in spike also subtended by small, white bract, X 0.4.-b. Individual flower dissected from rachis of spike to show absence of perianth, the six stamens, three styles, and inferior, compound ovary with many ovules on parietal placentae, X 6.-c. Fruiting spike with persistent bracts, X 0.6.-d. Cross section of ovary with ovules attached in two lines to each of the three parietal placentae, X 6.-e. Stamen, X 12.-f. Anasulcate pollen grain, ca. 13.5 µ long.-g. Globose seed, containing copious perisperm and rudimentary embryo, X 24. Nees ( also in India) , Laurus L. ( also in the Mediterranean region), Ocotea Aubl., and Persea. Reaching the south temperate areas are Beilschmieclia Nees, Cryptocarya R. Br., Cassytha, Ocotea, and Persea, the first three of which are also pantropical. Species of the tropical Cassytha, Licaria Aubl., and Ocotea ( including Nectanclra Rol. ex Rottb.) reach north into southern Florida. Separated from the rest of the Lauraceae, all trees or shrubs in the Lauroideae, are the species of Cassytha, which, because of their slender twining habit, scalelike leaves, and parasitic life style, are placed in the separate subfamily Cassythoideae ( Allen, 1945;Kasapligil, 1951;Sastri, 1952Sastri, , 1962Sastri, -1965Stern, 1954;and Kostermans, 1957).
HERNANDIACEAE Blume 1826.-The tropical Hernandiaceae differ from the closely related Lauraceae mainly in their epigynous, commonly unisexual flowers, more frequently lianous habit, often palmately-lobed or -dissected leaves, and the dry, ribbed nuts, frequently winged. Although Shutts (1960) advocated the removal of Gyrocarpus Jacq. and Sparattanthelium Mart. as the Gyrocarpaceae from the Hernandiaceae with Hernanclia L. and Illigera BL, Kubitzki ( 1969) preferred to retain the two groups as subfamilies. The rather large number of significant characteristics possessed in common by the two groups, just as in the various subfamilies of Monimiaceae, force me to agree with Kubitzki, though earlier I had accepted the two groups as distinct families. The differences in the stamens, stigmas, cotyledons, vessel elements, and cystoliths do signify that the two subfamiles are well marked, and probably diverged from common ancestry long ago. Hernanclia, Gyrocarpus, and Sparattanthelium all reach north into Mexico; and Hernanclia sonora L. ( sensu lato) and Gyrocarpus americanus Jacq., like Cassytha filiformis L. of the Lauraceae, are circumtropical, especially on sandy strands ( Shutts, 1960;Kubitzki, 1969).

Hairs multicell ular-uniseriate
16. Outer petals not saccate nor spurred, but wider or less deeply partite than inner petals ; stamens 4 and free.
17. Perennial, rhizomatous, scapose herb ; leaves all radical , deeply pinnatifid, fe rnlike; petals entire, inner narrower than outer; ovules 2-4 basal; fndts siliculiform, dehiscing by 2 valves; chromosome number, n = 9; monotype of Japan ( Ptericlo- . Perennial or annual , low herbs, branched from base; leaves, many radical, pinnately cut; petals not entire, outer trilobed, inner tripartite; ovules numerous on parietal placentae; fruits siliculiform, mostly breaking up into I-seeded sections, or rarely a dehiscent 2-valved silique; chromosome number, n = 8; monogeneric in Eurasia The Berberidales ( Ranunculales or Ranales sensu stricto) are a rather large order of mostly perennial herbs, shrubs, or lianas that appear to have close common origin with the more arborescent Annonales, particularly the Illiciineae. Unlike the Annonales, however, they lack the spherical secretory oil cells of parenchymatous tissues and the anasulcate or closely derived types of pollen grains so characteristic of that order. Their pollen grains are tricolpate or related types. Their stem anatony, in line with their more specialized herbaceous or lianous habit of growth, is relatively specialized: primary stems with vascular bundles in a ring, in two or more rings, or scattered, and, especially in woody species, separated by very broad pith rays; vessel elements with simple perforation plates ( or scalariform with few bars in the Lardizabalaceae and Hydrastis Ellis ex L.), alternate intervascular pitting, and medium to very short in length; parenchyma sparse and diffuse to paratracheal or absent; and fibrous tracheary elements with bordered, or more often, simple pits, sometimes septate and storied. Generally the berberidalean flower too has more specialized stamens and carpels than those characterizing members of the Annonales.
Despite their greater specialization in many features than most members of the Annonales, species of the Berberidales do retain many primitive features in their flowers, fruits, and seeds. The basically actinomorphic, bisexual flowers have separate parts many or indefinite in number, and arranged spirally or spirocyclically on a convex receptacle. The perianth, basically trimerous in several series, is frequently poorly differentiated. When "petals" are present, they usually appear to be petaloid nectaries. The apocarpous gynoecia usually mature into many-to several-seeded follicles or into clusters of few-or single-seeded berries, drupes, or achenes. Members of the Papaveraceae and Nigella L. of the Ranunculaceae, with syncarpous gynoecia, generally produce capsules. The usually anatropous ovules have a massive nucellus and two integuments and mature usually into seeds with a small embryo and abundant endosperm. In the Berberidaceae and Sargentodoxa Rehder & Wilson and those Menispermaceae with a definite number of stamens, the stamens are opposite the petals, which in hnn are often opposite the sepals. Throughout the order there is a strong tendency toward compound leaves and often further to greatly dissected leaves, all usually alternate and exstipulate. Like their annonalean cousins plants of this order are heavily endowed with isoquinoline or phenylalanine alkaloids. The Menispermaceae, for example, share nine alkaloids with the Berberidaceae, six each with the Fumarioideae and Rutaceae, five each with the Ranunculaceae and Lauraceae, three with the Monimiaceae, two each with the Papaveraceae ( s. s.), Magnoliaceae, Annonaceae, Buxaceae, and one with the Hernandiaceae and Aristolochiaceae ( Willamin & Schubert, 1961;Ernst, 1964).
Some of the more outstanding evolutionary trends obvious in the Berberidales beyond those expressed characteristically in the specialized habit, stem anatomy, and foliage of member species, are displayed in the flowers , fruit, and seeds. There is a strong tendency toward unisexuality, particularly well developed in the mostly monoecious Lardizabalaceae and dioecious Sargentocloxa and Menispermaceae. In Thalictrum L. of the Ranunculaceae unisexuality is part of the anemophilous syndrome. In most monoecious or dioecious species, however, the unisexual flowers generally retain vestiges of the missing sporophylls, as staminodia in the female and carpellodia in the male flowers. Apparently only one carpel is retained in the bisexual flowers of the Berberidaceae ( but see Chapman, 1936;Eames, 1961;and Kaute, 1963) and species of Actaea L. and Cimicifuga Wernischek of the Ranunculaceae. Similar strong reduction is found sometimes in other floral parts. The carpellate flower of Cissampelos L. of the Menispermaceae is reduced to one sepal, one petal, and one carpel with no staminodium. In most of the apocarpous families, there is also a strong tendency toward reduction of the ovules in the carpels to one, frequently with the carpel mah1ring subsequently into a one-seeded berry, drupe, or achene.
Connation of the carpels into a syncarpous pistil, in the Ranunculaceae found only in the partly connate carpels of some Helleborus L. species and in Nigella, becomes a diagnostic family characteristic for the closely related Papaveraceae. The apocarpous ancestry of the poppies is, however, indicated by the internal and derived apocarpy of members of the Platystemonoideae ( Ernst, 1967). Connation in the androecium is seen in members of the Lardizabalaceae and Menispermaceae.
Many stages in the differentiation of the perianth toward production of petals can be found among members of the Berberidales. The tepals may be sepaloid or petaloid, or the perianth may be differentiated into calyx and corolla ( Papaveraceae). In many plants, especially in the Ranunculaceae, the petals seem to be modified, nectariferous staminodia ( Honigblatter) , often tubular in shape. In the Delphiniinae of the Ranunculaceae and Fumarioideae of the Papaveraceae the flower is bilaterally symmetrical. SUBORDER BERBERIDINEAE LARDIZABALACEAE Decaisne 1839.-Despite their lianous habit and unisexual flowers, some species of the Lardizabalaceae seem to retain more primitive features than members of the other families. In some genera the stamens are broad, fleshy, and undifferentiated, with embedded extrorse sporangia, dehiscing longitudinally, and a massive connective with an elongated apex. At anthesis the separate carpels are open at the apex with a stigmatic crest, perhaps modified from a megasporophyll of the winteraceous type ( Payne and Seago, 1968) , and have ovules distributed submarginally or laterally on the ovary wall. Although usually functionally unisexual, the fowers generally retain vestiges of the nonfunctional sporophy lls, and Decaisnea Hook. f. & Thom., an upright shrub or small tree, has bisexual flowers. The fruits , though often fleshy and somewhat baccate, are basically many-seeded follicles.
The Lardizabalaceae consist of perhaps 40 species in eight genera, six in eastern Asia ( Akebia Decne., Decaisnea, H olboellia Wall., Parvatia Decne., Sinofranchetia ( Diels) Hemsl., and Stauntonia Wall.) and two in central Chile ( Boquila D ecne. and Larclizabala Ruiz & Pav.) , an extraor- ALISO [VoL. 8,No. 2 dinarily disjunct distribution ( Thorne, 1973 Laos and Tonkin. Stapf ( 1926), who established the family Sargentodoxaceae, described the species as looking like a plant resulting from the graft of the gynoecium of Schisanclra on a plant of the lardizabalaceous Sinofranchetia. This glabrous, dioecious climber has alternate, trifoliolate, deciduous leaves and small, racemose, trimerous, greenish-yellow, unisexual flowers with vestigial remnants of the nonfunctional sporophylls. Only the gynoecium deviates from the trimerous condition, and it has numerous, one-ovulate carpels arranged spirally on an elongated receptacle. The solitary seeds with different shape, testa, and hilum readily differentiate th e fruits of Sargentocloxa from those of Schisanclra. Transitions from entire, simple leaves to trifoliolate leaves have b een observed in th e young shoots. In the phloem are large secretory cells with tanniniferous contents similar to th e tannin-mucilage receptacles found in certain Menispermaceae, Schisandraceae, an d Caulophyllum of the Berberidaceae ( Stapf, 1926 ).
MENISPEl1MACEAE A. L. Jussieu 1789.-Surely close to the preceding lianous taxa and to the more shrubby or herbaceous Berberidaceae are the perhaps 370 species of 80 genera of Menisperrnaceae. These plants, mostly dioecious woody vines but varying in habit from h erbaceous twiners to moderatesized trees, differ markedly from th e Lardizabalaceae and from Sargentocloxa in having mostly simple, though sometimes lobed leaves with distally and/ or basally swollen p etioles; drupaceous fruits with bony, often curved and sculptured endocarp ; and seeds with often curved, folded, or cochleate embryo in sometimes ruminate endosperm. Some t axa lack endosperm in the mature seed. Menisperms are readily distinguished from the Berberidaceae by tl1eir lianous habit, unisexual flowers , apocarpous gynoecium, single ovule ( rarely two ) per carpel with micropyle directed up, and tl1e drupaceous fruits. The menispermaceous alkaloids shared with other members of the Berberidales and Annonales are discussed above. Primarily circurnb·opical, the Menispermaceae are represented in the United States by five species in four genera ( Calycocarpum Nutt. ex Gray, Cissampelos, Cocculus A. DC., and Menispermum L. ). No species are known from the Pacific states or from Europe. L., all T ertiary relicts also represented in eastern Asia. In western North America are Achlys DC., Berberis, Mahonia Nutt. (Fig. 7), and No. 2 couveria C. Morr. & Decne., only the last, a genus endemic to the Pacific Northwest, not also represented in northeastern Asia. Many botanists include Mahonia in Berberis. The two genera, or subgenera, are closely related but certainly as distinct from each other as many other widely accepted genera in western North America.
Members of the Berberidaceae are best defined by their bisexual, trimerous flowers with apparently single carpel ( Fig. 7 e) and definite number of stamens, some or all opposite the petals ( Fig. 7b); anthers mostly opening by flap like valves ( Fig. 7 d); and fleshy ( Fig. 7 c) or dry, nonfollicular, mostly indehiscent fruits. Some botanists, as Chapman ( 1936), Eames ( 1961), and Kaute ( 1963) , have suggested that the apparently solitary carpel is pseudomonomerous, actually two or three fused carpels with one or two of them suppressed. Occasional biloculate carpels in Berberis, Caulophyllum, Diphylleia, Nandina Thunb., and Epimedium L. ( Chapman, 1936) lend considerable weight to this suggestion but are offset by occasional specimens of Podophyllum with several pistils ( Ernst, 1964). Teratological examples frequently can be more confusing than clarifying. The similarity of the abundant alkaloids of species of Berberidaceae to those in members of the Menispermaceae has been mentioned above. The characte1istic yellow alkaloid berberine of the Berberidaceae and Menispermaceae is found also in the Ranunculaceae and Papaveraceae of this order, in the Annonaceae and Lauraceae of the related Annonales, and in the chemically similar Rutaceae ( Rowson, 1958;Willaman and Schubert, 1961).
As is customary in larger angiospennous families with several evolutionary lines, a number of somewhat divergent genera or groups of genera have been split off from the Berberidaceae and treated as distinct families, as the Nandinaceae, Leonticaceae, and Podophyllaceae. Since these are generally retained close to the obviously related Berberidaceae ( s. s.) anyway, they seem more logically treated as subfamilies within a broader Berberidaceae. Glaucidium Sieb. & Zucc. and Hydrastis, sometimes included in the Berberidaceae, fit better into the Ranunculaceae and are discussed below under that family. RANUNCULACEAE A. L. Jussieu 1789.-Also largely temperate or montane in distribution are the Ranunculaceae, a large family of perhaps 40 to 50 genera and 1,800 to 2,000 species. Represented in the United States are about 20 genera and 300 species, the majority of the latter belonging to such large genera as Ranunculus L. , Delphinium L., Aquilegia L., Anemone L., Clematis L ., and Thalictrum. Although ce1tainly closely related to the Berberidaceae, the members of the Ranunculaceae are somewhat more specialized in their habit of growth. Most are rhizomatous perennials, some are scandent or even woody vines, some annuals, and a few are shrubs. On the other hand, they are more primitive in their floral and fruit characteristics. Though the perianth usually lacks normal, conspicuous petals, the tepals are often petaloid, and frequently petaloid nectaries or honey-leaves are present. The stamens and carpels mostly are numerous, indefinite in number, separate, and spirally arranged on the often enlarged or elongated receptacle. The carpels have many to few ovules or only one ovule, and they ripen into clusters of follicles or achenes, rarely into berries or capsules. The largely rhizomatous herbs agree rather closely in appearance with the similar herbs of the Berberidaceae and Papaveraceae both in habit and in the often alternate, exstipulate, compound, or much dissected leaves. With the Berberidaceae they share at least seven alkaloids, five with the Menispermaceae, and five with the Papaveraceae, including the Fumarioideae ( Willaman and Schubert, 1961).
As with the Berberidaceae, various botanists have sought to elevate divergent taxa of the Ranunculaceae to family status, as the Hydrastidaceae, Kingdoniaceae, and Circaeasteraceae. All seem more logically retained in the Ranunculaceae as the Hydrastidoideae and the Kingdonioideae. Most divergent are Kingdonia and Circaeaster with their unilacunar nodes, freely terminating dichotomous leaf venation, apetalous, reduced flowers, orthotropous ovules, and distinctive chromosome number ( n = 15). Both genera combine highly specialized with rather primitive characteristics. Foster ( 1959Foster ( , 196la,b, 1963Foster and Arnott, 1960) has regarded the unilacunar node and open, dichotomous venation as representing the persistence of primitive features. It seems more likely that they are specializations associated with the moist, shaded habitats apparently preferred by these two species ( Die ls, 1932;J anchen, 1949).
Hyclrastis and Glauciclium, sometimes placed with the Berberidaceae or as a distinct family, do have the berberidaceous rhizomatous habit of growth and Glaucidium frequently has only one carpel. However, their flowers have numerous stamens, many to two carpels or one carpel, no petals or nectaries, and their leaves are simple and palmately lobed. They are distinguishable from the other Ranunculaceae by the absence of nectaries, ovules with longer outer integument, rather fleshy fruit, and distinctive haploid chromosome numbers of n = 10 and 13. Their chemistry is very similar to tl1at of the other Ranunculaceae ( Hammond, 1955;Jensen, 1968) but they possess several alkaloids in common also with the Berberidaceae ( Willaman and Schubert, 1961). They seem better treated as an intermediate group but close enough to the other ranunculads to warrant subfamily treatment in the Ranunculaceae (Kumazawa, 1938;Buchheim, 1964).
The long-standing division of the Ranunculaceae into the follicular-fruited Helleboroideae and achene-fruited Ranunculoideae has been shown to be artificial, for the achene in the ranunculoids is polyphyletic through reduction from the follicle in various helleboroid lineages. It seems better to combine the Helleboroideae, therefore, with the Ranunculoideae, and to recognize instead the division into the Thalictroideae and Ranunculoideae suggested primarily on cytotaxonomic grounds by Langlet ( 1932) and Greg01y ( 1941) , and supported by phytochemical and embryological investigations by Hegnauer ( 1965) , Jens en ( 1968) , Vijayaraghavan and Marwah (1969), and Ruijgrok (1967). Whether the Ranunculoideae should be further subdivided as suggested by Ruijgrok ( 1967) into those taxa containing ranunculine and those not producing it can be decided only ALISO [VoL. 8,No. 2 after we have accumulated more data. At any rate, the name Helleboroideae could not be used because both Ranunculus and Helleborus produce ranunculine. Paeonia L. has been properly removed from the Ranunculaceae, and it is now generally considered to constitute a distinct family. I have placed it in the Theales under the Dilleniineae and will discuss it later with that group.
SUBORDER PAPA VERINEAE PAPAVERACEAE A. L. Jussieu 1789.-The Papaveraceae (including the Fwnariaceae) are another sizable family of mostly temperate perennial herbs. It contains perhaps 44 genera and 625 species, mostly of the Northern Hemisphere with especially strong representation in western North America and in Asia. Among the better known western American genera are Argemone L., Coryclalis Ventenat, the woody tree poppy Denclromecon Benth., Dicentra Bernh., Eschscholzia Cham. in Nees, Papaver L., Platystemon Beuth. ( Fig. 8), and Romneya Harv. In tropical Mexico and farther south the most striking poppies are the arborescent species of Bocconia L. In eastern North America genera represented by native species are Acllumia Raf., Argemone, Coryclalis, Dicentra, Sanguinaria L., and Stylophorum Nutt.
Traditionally the Papaveraceae have been included with the Capparaceae and Brassicaceae and their relatives in the Rhoeadales, presumably because of the syncarpous gynoecium with parietal placentation and the sometimes siliquiform capsule with valvate dehiscence and false dissepiment. That these features represent evolutionary convergence is indicated by the fundamentally different embryology ( Lindley, 1836;Lebegue, 1952) and chemistry of the Papaveraceae and the Capparales. Like the other Berberidales, the species of Papaveraceae, including the Fumarioideae, are extremely rich in alkaloids, sharing at least six with tl1e Menispermaceae and five with the Ranunculaceae ( Rowson, 1958;Hegnauer, 1959Hegnauer, , 1961Hegnauer, , 1963Hegnauer, , 1964Hegnauer, , 1969aHegnauer, , b, 1971Willaman and Schubert, 1961). The Capparales are relatively poor in alkaloids but rich in mustard oil glucosides, which are unknown from the Papaveraceae and other Berberidales ( Buhr, 1936;Kjaer, 1963). Similarly, amyloid reserves in the pollen grains are lacking in the Capparales but present in the Papaveraceae and otl1er Polycarpicae (Auger- Barreau, 1964). The apocarpous origins of the papaveraceous gynoecium are indicated by the internal vascular anatomy of Meconella Nutt. and tl1e near-apocarpy of the fruits of Platystemon ( Fig. 8a, c, d) ( Ernst, 1967). The trimery of the bisexual flowers ( Fig. 8a, b) of the genera of the Platystemonoideae and some other papaveraceous genera as well as the often dissected leaves and rhizomatous herb growth habit of the poppies and fumitories are other berberidalean features.
If one accepts the basically berbe1idalean chemistry, growth habit, foliage, flowers, pollen ( Fig. Sf), and seeds of the Papaveraceae, then the family is still distinct enough in its characteristics to warrant separate subordinal treatment in the order as the Papaverineae. Especially distinctive from the Berberidineae are the syncarpy and parietal placentation ( Fig. 8c) of the gynoecium and the generally cyclic and dimerous perianth with the two or three sepals usually caducous and the two series of p etals conspicuous, polypetalous, often wrinkled, fugaceous , and without nectaries ( Fig. 8a,  b ). Also the usually numerous ovules are amphitropous or campylotropous rather than anatropous, and the fruits are often capsules dehiscing by two to many valves. The largest subfamily, Fumarioideae, represented in North America by the indigenous Corydalis, Dicentra, and Adlumia, and the introduced Fumaria L., is readily recognized by its bilaterally symmetrical flowers with one or both of the two outer p etals saccate or spurred, the two inner petals connate over the stigma, and the six stamens diadelphous. The sap of the fumitories is watery and secretory cells or idioblasts in the stem replace the laticiferous elements found in the poppies. More American than European botanists have tended to recognize this group as a distinct family Fumariaceae, possibly because the two intermediate genera, Hypecoum L. and Pteridophyllum Sieb. & Zucc., are restricted to the Old World. To accept the Fumarioideae as a distinct family one would have to ignore the basic papaveraceous habit, foliage, stem anatomy, chemistry, cytology, and fruits of the fumitories and the two listed intermediate genera with their mildly bilaterally symmeh·ical corollas and four free stamens. The three groups are more logically treated as subfamilies coordinate with the four subfamilies recognized by Ernst ( 1962) for the poppies, the seven having diverged over a long period from now extinct common ancestors.

ORDER NYMPHAEALES Lindley 1845
SYNOPTICAL KEY TO FAM ILIES AND SUBFAMILIES l. Plants mostly rhizomatous perennials ( Euryale annual ) with floating or emersed leaf blades long-petiolate, alternate, leathery, orbicular to sagittate, with basal sinus or peltate, and/ or submersed leaf blades opposite or whorled, petiolate, entire and filmy-thin or dichotomously divided into narrow segments; flowers bisexual, large or small but usually conspicuous, mostly long-pedunculate in leaf axils, with perianth; stamens and carpels various; pollen grains anasulcate or closely derived types or apparently t ri colpate; pollination entomophilous or "h ydrocleistogamous"; ovules anatropous, w ith two integuments; fruits and chromosome numbers various (Nymphaeaceae, sensu lato ) .

DISCUSSION OF THE NYMPHAEALES
The members of the Nymphaeales show their common origin with other taxa of the Annoniflorae by their retention of various primitive features, including xylem without vessels or with primitive tracheidlike vessel ele- ALISO [VoL. 8,No. 2 ments ( Nelumbo Adans.) ; bisexual , actinomorphic flowers with parts entirely separate, indefinite in number, and spirally arranged; perianth not at all or but poorly differentiated into sepals and petals; some stamens broad and undifferentiated into filament and anther; pollen grains anasulcate or closely derived therefrom; carpels separate to connate in varying degree; ovules relatively numerous, anatropous, bitegmic, and crassinucellate; and seeds with poorly developed embryo and abundant perisperm and some endosperm. In addition, they are well represented and ancient in the fossil record back into the early Cretaceous. Unlike members of the Annonales, however, no species of the Nymphaeales has been found to contain spherical secretory cells in their parenchymatous tissues. And unlike th e members of the Berb eridales, only the two species of Nelumbo in the Nymphaeales have apparently attained the tricolpate stage of development in tl1eir pollen grains, the other members of the order having anasulcate or closely derived types of pollen grains. As in both the Annonales and Berberidales, plants of the Nymphaeales, with the exception of the completely submersed species of Ceratophyllum L., have been found to produce alkaloids ( Willaman and Schubert, 1961) .
From the fossil record one can readily deduce that the Nymphaeales are a group that early diverged from protoannonalean stock by entering freshwater habitats and quickly becoming adapted to an aquatic existence. The ten extant genera of the order have evolved along their own evolutionary pathways for many tens of millions of years. As a result this relatively small handful, p erhaps 65 species, of survivors of an ancient group show an amazing diversity of characteristics, such a diversity that it prompted one botanist ( Li, 1955 ) to divide the Nymphaeaceae sensu lato into five families distributed over three orders. Such disintegration of the group is not only unnecessaiy, it is quite misleading. Nonetheless, I do feel now after considerable study that the Nymphaeaceae s. l. , as treated in the synoptical key above, do consist of five recognizable groups. These groups have gaps among them of sufficient magnih1de to warrant the acceptance of three distinct families, and three subfamilies within the Nymphaeaceae sensu stricto. Along with the Ceratophyllaceae, however, th ey retain enough characteristics in common to indicate their immediate common ancestry. In addition to th e features listed above by which I place them in the Annoniflorae, the members of tlrn Nymphaeales are linked by a number of characteristics that may not be convergent adaptations to their common aquatic habitat. Members of all three waterlily families , Nelumbonaceae, Cabombaceae, and Nymphaeaceae ( here and subsequently used in the narrow sense), have retained the b asic rhizomatous perennial herb habit of growth with very long petiolate, alternate, simple, floating or emersed, centrally peltate leaves witl1 involute vernation. There are, of course, deviations from this pattern because Euryale, at least , is annual; Cabomba Aubl., caulescent like Brasenia Schreb. and Ceratophyllum, sometimes has only submersed, highly dissected, opposite or whorled leaves ( also like Ceratophyllum); and most nyrnphaeaceous genera have nonpeltate floating pads with deep sinuses. These habital feahU"es , taken by themselves, cannot be decisive for they are all found, to at least a limited extent, in some representatives of unrelated families that have become adapted to the same freshwater habitat. But to be added to them are the scattered vascular bundles lacking secondary growth, articulated laticiferous tubes or sacs, often polystelic rhizomes and stolons, root hairs arising from specialized cells, mucilage hairs, other hairs only uniseriate, and anomocytic stomata. Other anatomical features, like abundant intercellular air spaces, absence of cambium, and highly reduced sclerenchymatous and xylem tissues, are more likely ecological convergences, as perhaps also are such reproductive characteristics as laminar placentation in the carpels ( also found in several aquatic monocotyledonous families), operculate seeds, and tardily dehiscent baccate or indehiscent fruits. Possibly nonconvergent are common tendencies toward cyclic and reduced number of floral parts, biseriate perianth, syncarpous, inferior ovary, or carpels and ovules few or even solitary, pollen grains modified from the anasulcate type, and large, well-developed embryos absorbing at maturity the endosperm and perisperm.
NELUMBONACEAE Dumortier 1829.-The Nelumbonaceae are represented by two species, Nelumbo lutea (Willd.) Pers., of eastern North America south through eastern Mexico and the Greater Antilles to Colombia and Guyana, and N . nucifera Gaertn., of China south through eastern Asia to Ceylon and Iran and through Malesia to northern Australia. The genus had a wider distribution in the Northern Hemisphere in Cretaceous and Tertiary times, apparently reaching northern Africa as well as Europe and western North America ( Thorne, 1973). These large aquatics with large, orbicular, glaucous, concave, peltate leaf blades and large yellowish, white, or pink, solitary flowers usually borne well above the water smface on stout petioles and peduncles, differ quite markedly from the other waterlilies in their tricolpate pollen grains ; much enlarged, spongy, obconical receptacles with embedded separate, acornlike, exceedingly long-lived nuts; nonoperculate seeds containing a large embryo witl1 two large, fleshy cotyledons, green plumule, and neitl1er endosperm nor perisperm; first foliage leaves peltate; primitive vessel elements; lack of mucilage hairs and laticifers; and a chromosome number of n = 8. Simon ( 1970Simon ( , 1971 found Nelumbo to be serologically rather isolated from tl1e other waterlilies, showing partial identity reactions with members of the Annonales and Berberidales as well as with other Nymphaeales. CAROMBACEAE A. Richard 1828.-The Cabombaceae are represented by the rnonotype Brasenia schreberi Gmel. ( Fig. 9) , of nearly subcosmopolitan but sporadic distribution (lacking from Europe and South America), and seven species of Cabomba, of warm-temperate to tropical parts of the New World. Though less widely recognized as a distinct family ( but see Lindley, 1836;Endlicher, 1839;Gray, 1848;Li, 1955;Snigirevskaya, 1955;Hutchinson, 1973;and Takhtajan, 1969) , tl1ese plants seem to deserve separate family treatment on the basis of their distinctive slender rhizomes ( Fig. 9a, g); caulescent, floating stems ( Fig. 9a) ; much dissected, opposite, submersed leaves in Cabomba; small flowers witl1 apparently cyclic, mostly ALISO [VoL. 8,No. 2 trimerous, biseriate perianth ( Fig. 9b, c) ; 36-3 specialized stamens; strictly anasulcate pollen grains ( Fig. 9h) ; 18-1 separate carpels containing three or two laterally or dorsally attached ovules ( Fig. 9c); and indehiscent nutlets with three to one pendulous seeds ( Fig. 9d,e) . Though strictly apocarpous like Nelumbo, the species of Brasenia and Cabomba in many characteristics are closer to the Nymphaeaceae, which they resemble especially in pollen morphology ( Fig. 9h) , seeds ( Fig. 9e) , seedling ontogeny, mucilage hairs, and laticif ers. The other genera have few to only one species, and are: Nuphar J.E. Smith with one polymorphic yellow-flowered species of North America and Eurasia and a few other poorly known species of eastern Asia ( Beal, 1956 ); Victoria Schomb. with huge, peltate, heavily ribbed, floating leaves of eastern lowland South America; Euryale and Barclaya Wall. of eastern and southeastern Asia; and the recently described Ondinea d. Hartog ( 1970) of northwestern Australia. These are acaulescent, rhizomatous, mostly perennial waterlilies with alternate, long-petiolate, thin or filmy, simple, cordate submersed leaves and leathery, peltate or deep-sinused floating or emersed leaves. They are readily distinguished from species of the Nelumbonaceae and Cabombaceae because of their usually large, showy flowers with numerous spirally arranged petals often passing gradually into staminodia and stamens, 35-5 variously united carpels tending strongly toward the perigynous or epigynous condition, numerous ovules distributed over the locule walls, radiate stigmas, and fruit a spongy irregularly dehiscent berry with numerous, often arillate seeds . The six genera of this family are divisible into three well-marked groups, as demonstrated in the synoptical key above. However, the differences certainly are not great enough to warrant the family status awarded them by Li (1955 Fig. 9. Brasenia schreberi Gmel. , Cabombaceae, sporadically subcosmopolitan in fresh water, representing the Nymphaeales.-a. Flowering caulescent aquatic with floating, alternate, elliptic, centrally peltate leaves and emersed, small, purplish flowers on branches arising from slender rhizomes that root at nodes, X 0.3.-b. Flower with six rather similar sepals and petals, 18-36 stamens, and six distinct carpels, X 1.3.-c. Flower matured into essentially ripe fruits, X 1.3.-Note that, as shown also in b and f, the submersed parts of the plant are covered by a thick layer of mucilaginous jelly.-d. Slenderly panduriform, two-seeded, indehiscent, nutlike fruit , X 2.-e. Globose, operculate, grayish seed, X 3.-f. Young submersed branch with buds, developing leaves, and stems all thickly covered with mucilaginous jelly, X 0.5.-g. Node of rhizome from bottom mud producing branch, leaves, and numerous fibrous roots, X 1.-h. Anasulcate pollen grains seen from different angles, ca. 58 µ. long. e on the lower smface and on the petiole with prickles; the completely inferior ovary with campanulate-urceolate floral tube; and the aculeate, baccate fruit. The Barclayoideae stat. nov. [based upon Barclayeae S. Endlicher, Gen. Pl. 900. 1839] consisting of the single genus Barclaya, also has a completely inferior ovary but the leaves are submersed, not floating, and oblong-orbicular to linear-lanceolate with hastate or cordate bases, neither orbicular nor peltate, and they are not armed with prickles. In addition, the elongate floral h1be is subtended by an involucre of five sepaloid bracts; the gynoecium is prolonged into a connivent ten-rayed stigmatic cone; and the nonaculeate baccate fruit has numerous softly setose seeds. The chromosome numbers in all three subfamilies are varied. The diversity of the Nymphaeaceae does not seem extraordinary for such an ancient group of relicts. CERATOPHYLLACEAE S. F. Gray 1821.-The Ceratophyllaceae, with perhaps six to ten species in the single genus Ceratophyllum, are probably the most ubiquitous submersed dicotyledons in cold temperate to tropical freshwater habitats. They require relatively warm water for fruit production, but C. demersum L. at least seems to reproduce and spread most rapidly by vegetative reproduction. They are beautifully adapted for their aquatic habitat with highly dissected leaves in whorls on slender stems completely lacking in roots, cuticle, stomata, and sclerenchymatous tissues. Specialization through reduction in the reproductive structures is also greatly advanced: flowers imperfect, naked, sessile, and minute with 20-10 fourloculate stamens or a single naked carpel with one suspended orthotropous ovule with only one integument. Pollination is hydrophilous by spherical, inaperturate, smooth, thin-exined pollen grains produced in great numbers. Species of Ceratophyllum resemble those of Cabomba most closely in their caulescent stems clothed with whorled leaves finely and dichotomously dissected and the single carpel ( as in Cabomba palaeformis Fassett). Plants of Cabomba frequently lack the peltate floating leaves, and then are completely submersed like Ceratophyllum except for the flowers. In some other respects Ceratophyllum more closely approximates Nelumbo, especially in the monocarpellate, indehiscent, one-seeded fruit which has a large embryo with large, . fleshy cotyledons, well-developed plumule, poorly developed or no radicle, and no endosperm nor perisperm. Other resemblances are the numerous extrorse stamens spirally arranged on a convex receptacle, prominent connective above the pollen sacs, and similar details of embryogeny.

ACKNOWLEDGMENTS
Space does not permit me to acknowledge all the help and encouragement I have received from numerous individuals over nearly 25 years of effort toward developing the classification of the Angiospermae presented in part here. More immediately, several of my esteemed colleagues have offered much information, advice, and encouragement, Sherwin Carlquist with numerous anatomical, palynological, and other details, Lee Lenz with cytotaxonomic data, and Richard Benjamin with general editorial advice. Michael Cole and Paula Nicholas have been most patient with my demands upon their considerable artistic skills in preparing their excellent original drawings. I, of course, am responsible for any mistakes that may have crept into the text or figures.
For plant materials, theses, or publications mshed to me recently during preparation of this study, I am particularly indebted to T. B. Croat, St. Louis; H. Eichler and R. Schodde