xChiranthofremontia, An Intergeneric Hybrid of Chiranthodendron Pentadactylon and Fremontodendron 'Pacific Sunset'

x Chiranthofremontia lenzii, an intergeneric hybrid between Chiranthodendron pentadactylon and Fremontodendron 'Pacific Sunset' (Sterculiaceae: Fremontodendreae), was made artifically and is described as a hybrid genus. It shows distinctive intermediacy in floral (particularly androecial) characteristics between the parental taxa.


INTRODUCTION
In June 1981, Austin Griffiths successfully completed a cross between the distinctive Mexican hand tree Chiranthodendron pentadactylon Larreategui (male parent) and a cultivated California Flannelbush or Fremontia Fremontodendron 'Pacific Sunset' (female parent), which is in tum of hybrid origin between Fremontodendron californicum (Torr.) Cov. and F. mexicanum A. Davids. The artifical hybrid, completed only after many attempts, is here described as a hybrid genus x Chiranthofremontia. RESULTS AND DISCUSSION x Chiranthofremontia lenzii Henrickson, gen. et sp. nov. Fig. IE-I A Fremontodendron dilfert foliis majoribus, periantho magis late cupuliformi, androecio irregulari floris in facie abaxiali antherae producente, tubo filamentorum superorum rima abaxiali, antheris thecis longioribus, et antherarum connectivis extensis caudatis; a Chiranthodendron dilfert foliis minoribus magis profunde lobatis, periantho ochroleuco vel flavi-aurantiaco, androecio tubo basali breviore, et antherarurn filamentis separatis. Rhomboid shrubs 3.5 m tall, 2m wide (at 5 years age) with 1-3 basal stems, stiff, ascending branches and full, open foliage; young stems 3-5 mm in diameter, densely light brown stellate-tomentose, the stellate hairs sessile and forming the understory vestiture, or stalked and with 20-32 translucent or red-tipped radii 0.2-0.3(-1) mm long extending from a thickened central trichome axis; older stems with vestiture turning dull brown, tardily glabrate, the underlying stems maroon-brown. Leaves alternate, borne on cylindrical petioles (2.2-)4-6.5(-8) em long; stipules thick-lanceolate, 5-9 mm long, stellate-tomentose; leaf blades orbicular to suborbicular in outline, horizontally oriented, palmately 5-7-veined and 5-7-lobed, (4.4-)6.5-10(-11.7) em long, (4.3-)6.2-9.5(-10.5) em wide with the smallest leaves borne at the base of a season's increment, the leaflobes acute to obtuse, apiculate at the tips, irregularly and shallowly toothed at the vein endings along the margins and with V-or U-shaped sinuses extending about one fourth to one third to the base, the lower lobes progressively smaller, the leaf bases deeply cordate with rounded, convex inner margins, the upper leaf surface dull olivegreen with the yellow primary veins impressed, sparsely stellate, the hairs with 19-25 tan to translucent radii 0.2-0.3 mm long, the lower leaf surfaces creamtan to rusty-tan, with the primary through the fourth or fifth order of veins raised, densely stellate-tomentose throughout with the hairs sessile or short stalked with 20-32 translucent or red-tipped radii 0.2-0.4 mm long, the red-tipped radii mostly occurring on hairs borne along the veins. Flowers solitary at the nodes, opposite the leaves, borne on stellate-tomentose peduncles 8-14 mm long; bracts 3, subtending the perianth, thick, lanceolate, stipulelike; perianths (calyces) erect-ascending, open-cupped, somewhat star-shaped as seen from above, the outer surfaces deep apricot-yellow with dull orange to orange-red on the outer thickened sepal bases, more yellowish on the protected, broader, inner lobes, the inner surface yellow distally, but blushed with apricot to orange-red near the inner bases and green in the nectary areas, 4-5 em long, deeply 5-lobed to within 8-10 mm of the base, each lobe with a well-developed midrib that curves upward then outward, the thinner margins curving toward inward near the tips, the outer three lobes thicker, more elliptical to ovate, 16-20 mm wide, acute and caudate at the tips, the inner two lobes thinner, more obovate, 19-25 mm wide, more abruptly rounded below the caudate tips, the lobes greatly thickened towards the base and each with a pronounced, thickened medial exterior keel that extends beyond the tip as a caudate appendage 5-9 mm long, and an interior nectary 6-8 mm long, 3-4 mm deep, radially sunken into the thickened base, densely stellate-tomentose where exposed in bud with hairs similar to those of the stem but less dense, the outer surface ofthe inner sepals that are covered in bud bearing scattered 3-rayed stellate hairs with radii 0.2-0.5 mm long, the outer lobes somewhat stellate about the tip inside otherwise the sepals glabrous inside except for stiff setae 1-1.5 mm long in and around the nectary and stalked multiseriate glands around the nectaries inside; androecium 45-49 mm long, yellow; filaments surrounding the ovary below, but separating above and bearing 5 slender, abaxial, caudate-tipped anthers distally; the basal filament tube obconic, 10-13 mm long, abruptly constricted above an expanded base, this opening abaxially for 5-7 mm below the individual 5-8-mm-long filaments; anthers introrse, 16-20 mm long, to 2 mm wide, each with a pair of somewhat contorted thecae, each separated longitudinally into two anther sacs by a membranous septum and each sac further separated by transverse membranous septa into discrete locules, the outermost anther sacs of the peripheral anthers extending further down the filament by 2-3 mm, the terminal sterile caudate appendages 3-5 mm long; pollen tricolporate, oblate, coarsely reticulate, 64 percent staining in Cotton Blue; styles 39-42 mm long, tapering, stigmatic and 5-lobed at the very tip, initially positioned behind the anthers, later elongating and extending between the anthers; ovary superior, 5-carpelled, covered by erectascending setae to 1.5 mm long. Fruit not maturing.

Taxonomic History o/Fremontodendron and Chiranthodendron
The taxonomic history of both parental genera has been confused. The genus Fremontodendron Coville (Coville 1893) has long been known by the earlier published name Fremontia Torrey (Torrey 1853) (actually validly prepublished by Torrey in 1851 according to Stafleu and Cowan [1986]). However, Torrey's Fremontia is a later homonym of Fremontia Torrey (in Fremont 1843), which is itself a synonym of Sarcobatus Nees von Esenbeck (1839) ofthe Chenopodiaceae. Attempts have been made to conserve Fremontia Torr. (1853) over Fremontia Torr. (1851), but conservation ofTorrey's later use ofthe name was not approved by the Nomenclature Committee of International Association of Plant Taxonomists by a narrow vote for 5 for and 6 against conservation (Pichi-Sermolli 1954). Munz (pers. comm.) misread the results of the committee's decision and erroneously used Fremontia Torr. (1853) in his A California Flora (Munz 1959). The genus was revised by Harvey in 1943; three species are recognized in the genus by the latest unpublished revision by Kelman (1983): Fremontodendron californicum from chaparral, pinyon-juniper woodlands to lower pine forests in California from Shasta County south to northern Baja California; F. mexicanum from dry chaparral and southern oak woodland in southern San Diego County and adjacent northern Baja California; and F. decumbens R. M. Lloyd from a limited area at high elevation in Eldorado County, California.
Chiranthodendron pentadactylon has also had a confused taxonomic history. The species was first described in a rather long discourse on "Descripciones de Plantas" by Joseph Dionisio Larreategui (1795), a Mexican botanist-physician, at the Royal Garden in Mexico whose director, at the time, was Don Vicente Cervantes. In the article he states the name of the genus was taken from that used by Sesse in his expedition to New Spain (Mexico). Portions of this article were later republished by Cervantes in Anales de Ciencias Naturales in Spain in 1803, under the sponsorship of the director of the Madrid Botanical Garden, Antonio Jose Cavanilles. However, in this article, Cavanilles notes that he is giving the plant the name Chirostemon rather than Chiranthodendron at the request of Cervantes. Larreategui's 1795 article was later translated, in part, by M. Lescallier and published, in French as "Description botanique du Chiranthodendron ... " in Paris in 1805 (Larreategui 1805) and again published in German in 1807 (Stafleu and Cowan 1979). Cervantes in his 1803 paper noted that Jacquin (1763) had listed the common name used for the plant by Hernandez in his Historfa de Mexico as a synonym for his Helicteres apetala Jacq. (Sterculiaceae), which Cervantes later changed to Cheirostemon apetalum in Roemer's "Collecteana" in 1806. Later, Humboldt and Bonpland (1808) described the same species in their "Plantae aequinoctiales" as Cheirostemon platanoides Humboldt & Bonpland. Chiranthodendron was corrected in Bentham and Hooker's Genera Plantarum (1862) to Cheiranthodendron, which he considered an orthographic change as the name is taken from Greek Xeir-anthos-dendron, meaning hand-flower-tree. Their orthographic change is not accepted here following Article 73.1 of the International Code of Botanical Nomenclature (Greuter et al. 1988), which deals with the retention of original spellings of names except in cases of typographic or orthographic error. When the Greek Cheir is transferred to Latin, the "ei" should be changed to "i" as "ei" is foreign to Latin (Dan Nicholson, pers. comm.). The Larre{ltegui (1795) and others report that, at the time of its various descriptions, the species was known only near the city of Toluca, in the state of Mexico where but a single tree existed, which was venerated by the local Indians who considered it the only tree of its kind in the world. This same tree was visited by many botanists including Sesse and Mociiio, Cervantes, and Humboldt and Bonpland. Later, in 1801, large populations were discovered in Guatemala and later elsewhere. The species is now known as often abundant in wet mixed oak-pine, deciduous, and occasionally elfin forests in mountains mostly between 1 700 and 3000 m elevation in Mexico in the states of Mexico, Morelos, Michoacan, Guerrero, Oaxaca, and Chiapas, but is more common in Guatamala where it is often the dominant tree on wet montane slopes and has trunks 90(-120) ft tall and 3-7 ft in diameter (Standley and Steyermark 1949;Toledo 197 5). In nature it flowers from February to May (later in cultivation). Common names include Mano de leon, Mano de Mico, Arbol de las manitas, and in Nahuatl Mapasuchil, Mac-palx6chitl, and Machpalxochiquahuitl meaning hand-flower. Vogel (1969) considers the flowers to be bat pollinated, but presents no field data to back his statements, while Toledo (1975) documents visitations to the flowers by various perching birds and considers these to be the major pollinators of the species.

Characteristics o/Chiranthodendron and Fremontodendron
As noted above Chiranthodendron (Fig. lA-D) is a large forest tree. Its leaves are broadly ovate to suborbicular, slightly lobed and oflarge size (15-31 em long, 15-27 em wide with petioles 8-17 em long). The leaves are initially stellate tomentose on both surfaces but later are mostly glabrate and green above, retaining a dense buff-tan to rusty stellate tomentum beneath. Leaf and stem vestiture is similar overall to that of the hybrid and Fremontodendron, except that the central axis of the stellate hairs is longer, and the longer-stalked hairs are thus more dendritic in shape. Flowers of Chiranthodendron are axillary, produced opposite the terminal stem leaves. The flower stalks are thick, to 2 em long, and bear 3 thick, lanceolate bracts 7-13 mm long. The flowers have cupular calyces 35 to 50 mm long that are thick, dark maroon-red in color and externally covered with a dull close tomentum (Fig. 1 B). The 5 sepals are separate to within about 13-15 mm of the base, and each ovate to oblong-ovate, erect sepal is greatly thickened and strongly keeled medially and basally, and the keel terminates as a caudate tip while the inner basal surface bears a deeply cut radially oriented, greenish nectary that contains large amounts of a thickened nectar. The stamens (Fig. lC, D) are much longer than in the hybrid, measuring 62-80 mm in total length, are more exserted and dull maroon-red in color. The basal continuous filament tube is 25-35 mm long and splits along the adaxial side 9-14 mm below the sessile anthers; distinct anther filaments are not present as in the hybrid and Fremontodendron. The anthers are erect-ascending, like fingers of a hand, and each anther bears two thecae 19-29 mm long with the thecae being separated into two anther sacs by a thin septum; the anther sacs lack transverse crosswalls (Fig. 1 C). The outermost anther sacs of the peripheral anthers extend 3-7 mm below the inner anther sacs. The caudate sterile connective tips extend some 13-21 mm above the anthers. Styles again are long exserted, to 4 em long. Fruit are oblong-ovate, tan tomentose, strongly 5-angled, woody, capsules 10-15 em long and 3-5 em wide. The seeds are obovate, lustrous black, with a globose, orange, basal aril.
In contrast, Fremontodendron ( Fig. 11-M) is a lower, much-branched shrub of chaparral, pinyon-juniper to yellow pine, and oak woodland habitats in California from Shasta County south to northern Baja California, Mexico, and east into Arizona. The palmately lobed and veined leaves are much smaller [15-40(-74) mm long, 8-40(-70) mm wide, with petioles 5-30(-70) mm long], and they may be deeply palmately lobed or nearly entire. They are initially stellate tomentose throughout, but become green and glabrate above while usually retaining some tomentum beneath. The flowers are similar to those of the hybrid in their yellow, often tinged with reddish-orange, color, but they are thinner in texture and much more open, more saucer-shaped at anthesis. The most distinctive difference is that in Fremontodendron the androecium is radially symmetrical (Fig. lK, L), the anthers are borne on separate, radiating filaments above the filament tube, and the connectives external to the anther sacs terminate at the tip of the anthers and do not continue as caudate claws. These structures are also much smaller than in either the hybrid or Chiranthodendron. In Fremontodendron the anther tubes range from 5 to 7.5 mm in length, the free filaments 3.5-5 mm in length and the anthers from 4 to 10 mm in length. As in the hybrid, the anther thecae are separated internally into two anther sacs and these are further transversely separated by membranous crosswalls (Fig. 1M).
The hybrid (Fig. 1 E-I) combines the characteristics of the two genera. It combines the more branched habit, yellowish flower color, and separate filaments of Fremontodendron with the thicker, more cup-shaped perianth and the longer, abaxially oriented, long-clawed anthers of Chiranthodendron. In addition, the surface on and around the internal perianth nectaries is covered with long setae similar to those found in some species of Fremontodendron. In contrast, the hybrid is intermediate in leaf size, leaf lobing, and vestiture between the two parental genera.
The close relationship of Chiranthodendron and Fremontodendron has long been known, and various authors have combined the two genera, Baillon (1872) making the combination Chiranthodendron californicum, and Coville (1893) recognizing the family Cheiranthodendraceae. At present they are distinguished within the Sterculiaceae in the tribe Fremontodendreae (Airy Shaw 196 5), characterized by having large flowers that lack petals, stamin odia, and an androgynophore, but have thick calyces with conspicuous internal nectaries and 5 stamens united in a basal stamina! tube. A nomenclatural conspectus of the tribe is presented in appendix 1.
The hybrid genus showed only 34 percent unstained pollen in Cotton Blue, the standard stain (Radford, Dickson, Massey, and Bell 1974) for evaluating the presence of potentially functional pollen. Lenz (1954) noted that artificial hybrids of F. californicum and F. mexicanum showed high pollen stainability and produced much seed.
The nothogeneric name is derived from the two generic names using "Chirantho" (hand, anther) and "Fremont" portions of the parental generic names. The species epithet honors Dr. Lee Wayne Lenz, Director Emeritis of Rancho Santa Ana Botanic Garden, who made many native hybrids, including Fremontodendron 'California Glory,' 'Pacific Sunset,' and 'San Gabriel' (Lenz 1954).
The new hybrid genus has been cultivated at Rancho Santa Ana Botanic Garden for six years and the plants, somewhat underwatered, have not yet taken on a mature growth form. A maximum height of 4 m has been obtained for cultigens thus far. The plants suffered through a series offrosts between December 22 1987, and January 1 1988, during which the temperature dipped below freezing every evening with minimal recorded temperatures reaching 24 F ( -4.5 C). The mature foliage survived this frost but all stem tips were killed back, resulting in reduced flowering the following year. Chiranthodendron is very frost sensitive and can only be cultivated in certain coastal regions in southern California such as at Santa Barbara. Fremontodendron, in contrast, is frost hardy and grows in areas receiving much snow. The