Vascular Flora of the Glass Mountain Region, Mono County, California

The purpose of this study is to document the vascular flora of the Glass Mountain region of Mono County, California. Little focused botanical attention has been given to this remote volcanic mountain range between the Sierra Nevada and White Mountains of eastern California. The majority of collecting in the area was done from the 1960s through 1998 by Dean W. Taylor, Mary DeDecker, and Jack Reveal, providing good documentation of a few scattered localities of the range. This study circumscribes a large area around the Glass Mountain range, and attempts to catalog the diversity of vascular plants with vouchered collections from many habitat types throughout the region. Field collecting and herbarium searches done from 1999 through 2002 have yielded 489 taxa (species, infraspecific taxa, and hybrids), building on the foundation of 181 taxa previously documented from the area. Sampling was done from low saltgrass meadows, through sagebrush series, into subalpine forests and meadows, and onto arid alpine peaks and ridges. An Annotated Catalog of the Flora lists the diversity of vascular plants documented in the region thus far. Vegetation descriptions. botanical collection history, numerical summaries, sensitive plants, and comparisons with other nearby floras are presented.

Approximately 27 km (16 mi ) northeast of the community of Mammoth Lakes, and 20 km (12 mi ) so uthwest of the hamlet of Benton (Fig . 2), the Glass Mountain mass extends 5 km (3 mi) southeast as a series of high vo lcanic ridges and domes (G lass Mountain Ridge) and west as the pumice plateau of Sentinel Meadow Re search Natural Area (RNA) . The study area encompasses approximately 725 km 2 (28 0 mi-) , w ith an elevational range of 1952 m (6400 ft ) at the base of Adobe Valley, to 3390 m (11,123 ft) at Glass Mountain peak .
In order to include as many distinct topogr aphic and habitat types ass oc iated w ith the range as possible, the circumscribed study area includes slopes and bajadas extend ing in all directions below this main mountain mass (Fig. 3) . Well defined paved roads (Highway 120 and Benton Crossing Road ) delineate most of the north, east, and so uth edges of the study are a. The upper Owens River-Deadman Creek drainages split the Glass Mountain region off from the rest of Long Valley. The western edge of the area is arbitrarily drawn from Owens Ri ver Road, up Highway 395 to Deadman Pass, and northeast on USFS Roads IS05 and I S06, terminating at Bi g Sand Flat and Highway 120.
These borders, althou gh somewh at arbitrar y, effectiv ely segregate the Gl ass Mountain Region from Granite Mountain on the north, Adobe Valley (in part) on the northeast, the Benton Range on the east, Casa Diablo MountainiChidago Canyon on the south, Long Valle y (in part ) to the so uthwest, Mono Craters to the we st , and the Mono Ba sin on the northwest. The alkaline si nks of Black Lake in Adobe Valley and Big and Little Alkali Lakes near the Hot Creek area of Long Valley border the study area but are not included within its boundaries.
Land ad ministratio n and ownership invol ve several entities. The majority of the study are a co ns ists of public land s administered by U. S. Department of Agriculture Inyo National Forest (lNF). W ithin their lands lie two Research Natural Areas: Indian a Summit and Sentinel Meadow. In add itio n to recreational use, INF regularly grants grazin g and logging permits in several are as of the region. After INF, the next largest land adm ini strator is the U. S. Department of the Int er ior Bu reau of Land M an agement (BLM), overseeing lower e lev atio ns of Long Valley and Adobe Valley. The City of Los Angeles (Los Angeles Department of Water and Power) control s so me lowlands adjacent to the O wens Ri ver in Lon g Valle y. Fin all y, scattered throughout the range are small pri vate inholdings , mostly ranches around the uppe r Owens River a nd Adobe Creek are a. A few historical and active mines oc cur in the region , all associated with granitic substra tes . Road access into the region is excellent via numerous INF and logging roads den sely interweaving the region. These roads, some of them more than 100 years old, are in different states of repair, from improved Mono County graded roads to narrow stee p j eep trails. The only areas of the region not ea sil y access ible by four-wheel dri ve vehicles are the Glass Mountain Peak and Ridge, Sentinel Meadow RNA, a nd the Black Mountain Ridge .

SU RV EY IVIETHODS
A total of 67 field collecting day s were spent in the region from 1999 through 2002, with the majority of work done in 2000 and 200 I . Although some tax a were in collectable co nditio n in late April-earl y May, the best collecting times for the regi on were late May through September, with flowering and fruiting generally following a low-to high-elevati on sequence . As many different habitats as pos sible were documented, sometimes comprehensively (all vascular plants of a local ity vouchered) . Because of the prevalence of widespread species such as Artemisia tridentata, Purshia tridentata, Elymus elymoides, and some conifers, not all areas were comprehensively vouchered. In these cases the particular taxa collected a lways included clear descriptions of these associated spec ies on the herbarium labels. Standard herb arium voucher specimens were collected in flower and/or fruit , and usuall y pressed in the field . Associated data included exact locality (fro m 7.5' USGS quad s), township and range, GPS coordinate s (decimal degrees), general habitat, slope aspect, elevation , substrate , associated species, and phenotypic data (e .g ., flower color, fruiting ). All the se data were entered into the Rancho Santa Ana Bot anic Garden Herbarium (RSA-POM) specimen database and appear on all herbarium specimen labels. Determinations were made using The Jepson Manual: Higher Plants of California (Hic kman 1993), and the Int ermountain Flora series (Cronquist et al. 1972 ;Cronquist et al. 1977;Cronquist et al. 1984;Barneby 1989;Cronquist 1994;Cronquist e t al. 1997), and through compari son with specimens housed in RSA-POM. All nomenclature conforms strictly to Hickman (1993 ) with exception of new treatments in Polemoniaceae, as annotated in The Jepson Desert Manual (Baldwin et al. 2002). Specimens were mounted on standard herbarium sheets, and deposited at RSA-POM, with duplicates to be sent to UCIJEPS , New York Botanical Garden (NY), and in some cases to Inyo National Forest and BLM.
Herbarium searches were conducted to find and include previous collectors' efforts from the area. The Rancho Santa An a Bot anic Garden Herbarium (RSA-POM ) was manu ally searched , producing 146 specimens. The University of California (UC) and Jep son Herbari a (JEPS) in Berkeley were first searched remotel y via the SMASCH online database, and then visited personally to co nduc t additional sea rc hes and verify determinations of spec ime ns, adding another 104 specime ns to the data set. All specimens from these herbarium searches were verified by the author firsth and, and occa sionally annotated with new det ermination s and/or updated nomenclature.
Field collecting and herbarium searches were com-pleted in 2002. Efforts were made to VISit as many different habitat types and localities as possible. Important areas needing additional exploration are the granitic peaks and slopes throughout the region, especially Black Mountain and the Wildrose Canyon! Kelty Canyon vicinity, which may still harbor new taxa specific to this substrate. The dense Jeffrey pine forests and slopes of the western part of the range have the potential to yield new vouchers (e.g., Chrysolepis sempervirens). Closer examination of the north-side meadows may add a few taxa to the flora. With the discovery of Arabis pinrlae near the Sierra crest (Constantine-Shull and Sawyer 2000), high-elevation Glass Mountain peaks and ridges could potentially support this taxon , known previously only from the White Mountains. Additional appropriate herbaria to search include the California Academy of Sciences Herbarium (CAS), and the New York Botanical Garden Herbarium (NY) which was searched online, but produced no specimens from the area not already represented as duplicates at RSA-POM or UCIJEPS.

Physiography
Digital elevation models (Fig. 3) provide a good reference from which to describe the major topographic features of the study area. The southwest edge of the range exhibits the most conspicuous relief of the area in the steep curved escarpment leading down from Glass Mountain Peak, Glass Mountain Ridge, and Sentinel Meadow RNA, into Long Valley. This was formed by the northeast arc of the Long Valley ring fracture caldera, which abruptly truncated and buried the preexisting lavas and tuffs of the range. The south edge of Bald Mountain was likewise sheared off and downfaulted . The Long Valley portion of the study area is relatively flat alluvial plain, with a few Pleistocene lake margin terraces, gently sloping towards Owens River (Mayo 1934).
The western quarter of the range exhibits relatively smooth topography of gently rolling forested hills. This reflects the recent eruptions of the Mono-Inyo Craters chain which have repeatedly coated the area with windblown pumice ash and gravel, effectively blanketing and smoothing-out any hard relief under dozens of meters of porous alluvium.
Along the north edge of the study area there are numerous deep canyons cutting northeast from the headwaters below Sentinel Meadow RNA and Glass Mountain Peak, all draining to Adobe Valley. The western edge of Adobe Valley is marked by a northtrending faulted system of granitic ridges and Peaks running from Sagehen Peak (2802 m) to Baxter Spring (Bailey 1989). Runoff from these headwaters collectively cut through Bishop Tuff formation , forming the deep North Canyon, paralleling H ighway 120. The conspicuous parallel narrow drainages of Dexter Canyon and Wet Canyon likewise cut through Bishop Tuff, and provide the majority of surface flow to Adobe Creek. Farther to the east lie Taylor Canyon and McGee Canyon, delivering their flows to Adobe Creek as well. Below the northeast flank of Glass Mountain peak, the two major canyons draining towards Adobe Valley are the Dry Fork and Wet Fork of Black Canyon.
On the east margin of the study area lies Black Mountain, a 7 km long granitic ridge northeast of Glass Mountain peak. Running north-south, Black Mountain exhibits the typical Great Basin structure of an east-tilted fault block (Hunt 1974). Many subsidiary "splinter faults" ripple the slopes east, creating a series of small rocky ridges leading down into the lowermost tip of Adobe Valley. Within this landform lie Klondike Canyon, Frazier Canyon, and Kelty Canyon. This granitic substrate continues south as occasional rocky outcrops and ridges throughout Kelty Meadows, Wildrose Canyon, Clover Patch, and the Deer Spring area.

Major Drainages
There are no direct snowmelt surface streams associated with the range, although the porous substrate of the Glass Mountain mass is a considerable groundwater reservoir, and feeds several perennial springfed streams and associated riparian zones. Many other " streams" appearing on USGS quads are subsurface drainages, traveling below the dry creekbeds and only apparent by the existence of phreatophytic indicator shrubs (e.g., Salix exigua and Rosa woodsii). Presumably in very wet years there would be intermittent surface flow, but these drainages appeared as dry washes during the study years of 1999-2002. Several form Wet Fork, which goes underground before reaching Adobe Valley. Deadman Creek/Owens River is the only major drainage emanating from outside the borders of the Glass Mountain Region. This strong perennial Sierran snowmelt creek defines the southwest edge of the study area, flowing to Lake Crowley, and eventually via two aqueducts to the faucets and hosebibs of the City of Los Angeles.

Geology
Because of its proximity to the Long Valley Caldera, the geology of the Glass Mountain Region is well known and mapped. A good review of the geological history and structure, including a detailed map, appears in Bailey (I989) (Fig. 4).
The Glass Mountain mass was formed by numerous volcanic venting episodes burning up through the preexisting Sierran granodiorite batholith, from 3.6 to 0.8 million years ago. These eruptions first deposited the basaltic and andesite flows and domes of McLaughlin Springs, Glass Mountain Ridge, and Bald Mountain. Thereafter Glass Mountain itsel f arose through successive venting of high-silica rhyolite in overlapping domes, flows, and tuffs. Rising over J 000 m above the basement rock, Glass Mountain gets its name from the coarse black obsidian fragments scattered around the white pumice and rhyolite rocks on its summit and flanks.
Nothing has had a more profound affect on the physiography of the region as the catastrophic eruption of the Long Valley Caldera (approximately 730,000 years ago). In a series of violent episodes, a huge magma chamber under what is now Long Valley erupted through an elliptical "ring fracture," discharging to the surface approximately 600 krn' of hot incandescent ash flows. This welded pyroclastic deposition formed the Bishop Tuff, inundating 1500 km 2 of the countryside south to Bishop, and north into the Mono Basin. This Bishop Tuff formation can be up to 200 m thick, and has a characteristic orange-pink color. It forms the bedrock through which Taylor Canyon, Wet Canyon, and  The Glass Mountain region experiences typical Great Ba sin climatic regimes of freezing winters and hot summers. Most precipitation fall s as snow in the winter months from November to March . Infrequent s u m me r thunderstorms account for only a sma ll amount of the yearly total. Prevailing wind s are from the we st, and are especially strong on exposed ridgeline s and high elevations. No temperature stations exist in the region, but similar averages for the area can be inferred from three nearby localities, of which Bodie is the closest to Glass Mountain in elevation and topography (Table I).
Few detailed long-term climatic records exi st for the Glass Mountain Region. Only one precipitation station ( 12.9  10 0 is active in the area, located in Jeffrey pine fore st, elevation 231 8 m (7600 ft ) at Crestview on the far southwest corner of the study area. An automated reporting station operated by INF, Crestview has recorded hourly precipitation (with some gaps) from 1995 to present (California Department of Water Resources 2002). These records indicate average yearly pre cipitation of 35 .3 c m ( 13. 19 in.) for the 7-year period, with heaviest ac cumulated precipitation in November-March (Fig. 5) . Thi s short reporting period includes two "EI Nino" e ve nts ( 1995 and 1998) and may therefore reflect skewed a verages for annual precipitation.
Other adjacent areas have better long-term recording stations and can provide concordant climatic data from which to infer conditions in the Glass Mountain area (Table 2). From these data, it is possible to estimate precipitation patterns across the region: Low areas around Long Valley and Adobe Valley: ± 15-25 ern (6-10 in.)/yr.
Mid-elevation fore sts and slopes: ± 25-45 em (l0-18 in.)/yr.   (Mayo 1934). Numerous post-caldera eruptions have had a significant effect on the Glass Mountain region. The conspicuous domes and ridges of the Mono Craters erupted from 40,000 years ago to as recently as AD 1365 (Sieh and Bursik 1986). Even more recent eruptions along the Inyo Craters chain have occurred as recently as 650-550 years ago (Miller 1985). The sig nificance of these eruptions is that wind-blown ashfalls have repeatedly blanketed the west Gla ss Mountain region over millenia, coating the area with soft, exceptionally well-drained ashy pumice soil.
Today the geology of the region is dominated by a land scape of volcanic domes, flows , tuffs, and ashfalls around the periphery of the caldera margin. The dominant bedrock varies from rhyolite, to basalt, to quartz andesite. Granitic bedrock is common throughout the eastern slopes and hi IJs of the area, around the Sagehen Meadow area, and along the north escarpment of Long Valley. Over all these different bedrocks can be found deep pumice ash and gravel, deposited by the prevailing we sterly winds.

HUMAN HISTORY
Paiute Indians from the Mono Basin and Owens Valley seasonally inhabited areas of the region before the arrival of European settlers. Evidence of habitations exist in the form of "house ring" foundations in the Pinyon woodland areas of the east-side of the region. Pinyon nuts (Pinus monophylla) were the most important food staple of these groups, and seasonal trips were made for harvesting and processing. Paiutes also harvested the grain of Indian rice grass (Achnatherum hymenoides), Great Basin wild rye (Leymus cinereus) and desert needlegrass (Achnatherum speciosum) (Liljeblad and Fowler 1986) . In the Jeffrey pine forests of the west side of the range there can be found shallow trenches dug around the larger trees. These were used up until the early 1900s to gather larvae of the pandora moth, Coloradia pandora, which in alternate years feeds on Jeffrey pine needles. Baked and dried, they were also an important part of the Paiute diet (Schoenherr 1992).
By the mid-1800s white settlement began in the Owens Valley and Mono Basin. Ranching became common in the sagebrush slopes and meadows, and hardrock mining was expanding throughout the greater region. The boom town of Bodie was in full swing in the late 1880s, and required large amounts of timber for building and charcoal production. Eyeing the vast slopes of Jeffrey pine forest in the Glass Mountain Region, a company was formed to build a 32-mile railroad to Mono Mills, where lumber was abundant (Wright 1993). This resulted in the grading of a web of logging roads deep into the region, and heavy cutting of the old growth Jeffrey pines. Many old stumps can be seen in what is now second-growth forest. Logging, on a much reduced scale, continues to this day, usually from permitted firewood cutting and INF thinning operations.
Two Research Natural Areas (RNA), administered by Inyo National Forest, are within the Glass Mountain Region. RNAs are selected to preserve outstanding examples of natural ecosystems for research and educational use, and to protect habitats of rare and endangered species (Keeler-Wolf 1990). Indiana Summit RNA was established in 1932 as California's first RNA . Its target element is the extensive pure stand of Jeffrey pine in the western part of the region. Sentinel Meadow RNA, established in 1983, covers the large pumice plateau and slopes west of Glass Mountain peak. The target elements here were lodgepole pine and limber pine. Good synopses of ecological surveys for both of these areas appear in Keeler-Wolf (1990) .
Other contemporary uses of the region are wide-spread cattle ranching, sheep grazing, occasional mines, and recreation . There are several INF campgrounds in the area, and numerous four-wheel drive trai Is throughout the region. Occasionally hunters, campers, all-terrain vehicle riders, fishermen, and shepherds are encountered in the field, but the region is never heavily used at anyone time, except by cows and sheep.

BOTANICAL HISTORY
Many areas around the Glass Mountain region have benefited from thorough floristic inventories. Notable among these are the published floras of the White Mountains (Lloyd and Mitchell 1973;Morefield et al. 1988); the Valentine Eastern Sierra Reserve (Howald [98 l ); the Fish Slough vicinity (Forbes et al. 1988); the Upper Walker River region (Lavin 1983); the Sweetwater Mountains (Hunter and Johnson J 983); the Rock Creek Lake Basin (Pierson 1938); and the Bishop Creek drainage (Crowther and Crowther 2002 In the early 1960s, Jack L. Reveal, while working for the USFS in the Mono Basin, made several forays into the interior of the region, documenting many new occurrences (Reveal 1972  Mary DeDecker, the intrepid Eastern Sierra botanist and writer, was the next collector to make significant documentation in the region. As a contract worker for Inyo Nat ion al Forest in 1974 and 1975, DeDecker compiled a checklist of the vascular plant s of the Obsidia n Plateau Lodgep ol e RNA, later ren amed Sentinel Me adow RNA (M. DeDecker unpubl. ). In 1984, ass isted by Bristlecone Chapter CNPS members, she made man y new vouchers from the meadows and granitic slopes around Sawmill Meadow a nd the Black Canyon drain age s.
In 1977, De an W. Taylor arrived in the region to do an ecological sur vey of the Indi an a Summ it RNA (Keeler-Wol f 1990), achie ving good do cumentat ion around the e xten sive virgin Jeffre y pine forests of this are a . In add itio n to qu antifyin g den sit ies and cover of the target speci es Pinus jeffreyi, Taylor de scribed much of the ecol ogy , natural history, and vegeta tion types of the RNA. That yea r he also repeatedly asc ended Glass Mountain peak, and collected at Crooked Meadows, Big Sand Flat, Little Sand Flat, and Clark Canyon.
Pursuing an ongoing interest in compiling a flora of Mono County, Taylor has repeatedly vis ited the area throughout the 1980 s and 1990s, do cumenting man y s pec ies from Watterson Canyon , Gl as s M ounta in Rid ge, Kelt y Meadows, Benton Crossin g in Long Valley , and most recently at Sawmill Me ad ow .
Steve Talley also performed an ecologi cal sur vey of the Sentinel Meadow RNA in 1978, building on the baseline data compiled by Mary DeDecker (Keeler-Wolf 1990 ). Although none of his collections have been found at RSA-POM or UCIJEPS, he sum mari zed basic ec ological and veg etation type s for the are a, in addition to qu antifying density a nd co ver o f the two target species , Pinu s co nto rta ss p. mu rrayana, and Pinus fi exilis.
The curre nt study retraces man y of the path s of the early coll ector s, and builds upon their initial findings. A summary of botanical collection in the region to date is presented in Table 3. Figure 6 map s co llection localities by major collectors in the area . VEGETATION Distribution and grouping of plants is determined by the inter action of many biotic and a bio tic factors. Over time, research er s have recognized many di fferent recurring assembl ages of plants and hav e atte mpted to classify them variously as "formations," " vegetation types," "plant communities," "alliances," "series, " and "association s. " Unfortunately, few local ities share the exact same species co m pos itions across the landsca pe. Intergradat ion between vege tation types further confounds exact c lass ifica tion: " T he probl em of fuzzy boundaries is cha rac teris tic of veg etation science " (Sawyer and Keeler-Wol f 1995). Nevertheless, se vera l Fig. 6. Coll ection localit ies of four maj or co llec to rs in the Glass Mountain Region. R = Jack L. Reveal, 1962Reveal, -1963D Mary DeDecker, 1955 ; T = Dean W. Taylor, 1977W. Taylor, -1998; H = Michael Honer. 1999 identifiable vegetation types occurring in the western United States can be found in the Glass Mountain Region. Listing them and their constituent spec ies ca n be useful as a predictor of occurrence and habitat of many particular species. Many different classification sy stems have been implemented in the last 100 years. A good contemporary system in use in California is A Manual of California Vegetation (Sawyer and Keeler-Wolf 1995). This system uses the "dominance rule" to identify the one or two species with the most cover in the vegetation. These dominant species are used to name "series," the basic vegetation unit. Within each series are lists of "associ ations," or spec ies commonly associated with the dominant plant. It is difficult to assign all of the associations encountered in the G lass Mountain Region into the series in th is sy stem. However, since this system is in wide use and is constantly being revi sed and improved, it is important to include the relevant series in the following vegetation descriptions.
For ease of description and interpretation, thi s study will so rt vegetation into four ba sic groups:

Shrublands
Low-elevation Sagebrush scr ub.-Sage brush scrub is the most ubiquitous vegetation type throughout the region, dominating all low valleys and slopes, and running up into Pinyon woodland s and fore st understory. Flourishing on well-drained sandy and gravelly soil s, thi s assemblage is dominated by its namesake, Great Basin Sagebrush, Artemisia trideniata ssp . tridentata. Typically open in cover, Sagebrush scrub is often a mo saic of different perennial shrubs with a high di-Understory species vary by habitat. Mesic strea m and meadow species are associated with the Lodgepole series throughout the region .
Mi xed conife ro us forests. -The coniferous forested flats and slopes of the region occur from the Pinyon zone up to Glass Mountain peak. Species distributions follow a general elevation/habitat sequence (w ith much intergradation) from low to high elevations: the perimeter of the region (2000-2400 m) , and best developed on (but not restricted to) rocky granitic substrate. Rarified Sagebrush scrub associations are common in the understory. Pinyon woodland s can best be seen along the granite ridges of Klondike Canyon and other east-side slopes (Singleleaf pinyon series).
DOMINANT: Pinus monophylla. SHRUBS AND TREES : Sagebrush scrub (most spp. listed above), Amelanchier utahensis, Eriogonum umbellatum, Ribes ce reum, R. velutinum Limber pine woodlands.-Pinus fiexilis woodland is common along higher slopes and exposed ridgelines throughout the region. Best developed on north-and ea st-facing slopes just below Sentinel Meadow RNA and Glass Mountain peak, this series is often tran sitional between lodgepole and whitebark pine series. Rare individuals can be seen in lower elevation scrub. Krummholzed dwarfed stands are common on the ridges overlooking Long Valley. The understory is usually scant (Lim be r pine series Whitebark pine woodland.-Common on pumice slopes and exposed ridges above 3000 m, Pinus albicaulis is the only true alpine tree in the region . On the high dry windswept summit plateau of Glass Mountain peak, it forms dense clonal sta nds only 1.5 m high. Taller individuals cling to rocky ridges and north-and east-facing slopes. It is best represented on Glass Mountain Pe ak and ridges , quickly disappearing downslope (Whitebark pine series). DOMINANT

Special Habitats
High altitude pumice plateaus and ridges.-Windswept pumice flats and slopes above 3000 m support a unique alpine flora. Best described as Parry rabbitbrush series, this sparse depauperate vegetation grows on well drained, often stony pavement with fine soil.
Most precipitation on these high plateaus falls as snow, but may be quickly blown off eastward by the strong prevailing winds of these high elevations. It is best developed on Glass Mountain summit plateau, 3300 m (close to Parry rabbitbrush series). DOMINANT Sand flats.-Several large "sand flats" of nearly shrubless gravelly pumice soil surrounded by Jeffrey pine forest occur around 2400 m in the western half of the region. Exceptionally well drained soil on these flats support a sparse layer of herbs which make up a distinctive series, not described in Sawyer and Keeler-Wolf (1995 Introduced grasslands.-A recent introduced vegetation type to the Glass Mountain Region is easily recognized as the cheatgrass series. Dominated by dense cover of the Eurasian invasive grass Bromus tectorum, it is best experienced on the steep burnt slopes on the north edge of Long Valley, from O'Harrel Canyon to Bald Mountain . What was once Pinyon woodland with Sagebrush sc ru b understory is now a nearly continuous sea of Bromus. Only occasional emergent recovering shrubs can be seen. Because of its short lifecycle, flammability, aggressive competition, and high productivity, the cheatgrass series is expected to persist and expand its range on these slopes and beyond, propelled in its hegemony by the increased fire periodicity it causes (Billings 1990) (Cheatgrass series) .

Non-Native Taxa
Non-native ("introduced " ) taxa account for only 2.9% of the total flora . Of the 14 taxa documented in the Glass Mountain Region , most exist in disturbed and ruderal areas (Salsola tagus; Descurainia sophia), and meadows tCirsium vul gare; Taraxacum officina- Ie). Non-native taxa are designated in the Annotated Catalog with an asterisk (*).
The most conspicuously invasive introduced plant is cheatgrass, Bromus tectorum. which has invaded large areas of the north edge of Long Valley. Introduced in the late 1800s in British Columbia, cheatgrass quickly spread south into the Great Basin, finding a niche in overgrazed Sagebrush scrub (Billings 1990). A hardy winter annual from Eurasia, B. tectorum completes its life cycle by late May, when it drops its seeds, dries up, and becomes brittle tinder for fires. Native shrubs such as Artemisia tridentata and Purshia tridentata get incinerated by these fires and are slow to reestablish, but Bromus survives well and proliferates, increasing the periodicity of such fires. As a result, what was once intact native Sagebrush scrub and Pinyon woodland is now a sea of Introduced grassland. These grassy burnt slopes reach up into the Jeffrey pine belt, which now exists under threat by such fires.

Comparative Floristics
Several floristic inventories have been completed for areas surrounding the Glass Mountain Region . Although a rigorous analysis between floras is beyond the scope of this paper, comparing floristic composition between these areas and Glass Mountain can provide a generalized view of the diversity of Glass Mountain in relation to these surrounding regions. A good way to evaluate overall similarity between floras is by using the Sorensen Similarity Index (SO, which uses taxon presence/absence data to render similarity on a scale of 0 to 100. This index is commonly used because it gives weight to species in common between areas, rather than those that are unique to each area (Kent and Coker 1992). Easy to calculate, SI is expressed as : SI = 2C/A + B X 100%; where C = number of taxa common to both areas, A = number of taxa in one area, and B = number of taxa in the other area.
Five nearby floras were selected to compare with the Glass Mountain Region. These were chosen for I) proximity to Glass Mountain, 2) availability of reasonably complete species lists, and 3) representation of similar and/or different floristic provinces. Table 5 lists the comparative floras used for this paper, citations, total taxa, and taxa in common with the Glass Mountain Region. Optimal comparisons require similar sample size (total surface area of floras) but, with the exception of the Bodie Hills, this was not feasible. The five floras chosen have widely varying elevational ranges, moisture gradients, substrates, species richness, and presumably different intensities of botanical documentation. Nevertheless, they can provide useful data with which to generate general comparisons with the Glass Mountain Region. Figure 7 summarizes the results.
Not surprisingly, the Bodie Hills Flora is the most similar (SI = 54) to the Glass Mountain Region . This may be accounted for by similar size, elevation range, position in the rainshadow side of the Sierra Nevada, and mostly volcanic substrate. The next most similar flora is the Bishop Creek drainage (SI = 49), which has similar east-side exposure, but with a richer flora, wider elevational range and moisture gradients, more non-native taxa, and predominantly granitic substrate. The White Mountains are in third position of similarity (SI = 43), differing from Glass Mountain by having a larger study area, greater elevation range, and many more diverse substrates. The Toiyabe Mountains were chosen to represent the Great Basin floristic province. Although having similar elevational ranges to Glass Mountain, they have a much larger sampling area and larger flora, rendering their similarity at 41 . Finally, Yosemite National Park was selected to represent west-side Sierra flora. Again, a much larger sample area, very high elevational ranges, higher annual precipitation, and very rich flora with strong cismontane components renders the similarity to Glass Mountain at only 28 .
All five east-side floras , when compared with each other, have an averaged similarity of 44.9. Comparing these five floras as a group to the west-side Yosemite National Park yields an averaged similarity of 31.2. This reinforces stronger affinities of east-side floras, including the Glass Mountain Region, with the Great Basin floristic province rather than with the more mesic cismontane affinities of the west-slope of the Sierra Nevada floristic province.  Thi s vo lume lists hundreds of taxa within the state, with annotations about occurrences, threats, taxonomic referen ce sources, and a specific rating system for rarity and threats. Although CNPS listing holds no direct statutory status, it is still the basis for ongoing legal action due to its widely cited documentation of sensitive plants throughout the state.
Twenty one taxa of spec ial status are documented within the Glass Mountain Region . Two are California State listed as Rare, Astragalus monoen sis var. mon- This study bases its data on fieldwork and vouchered collections verified by the author firsth and at RSA-POM and UCIJEPS. Several sources (sometimes referred to as "grey literature") allude to tax a that were not found in these herbarium searches. Although these taxa do not appear in the Annotated Catalog they are listed in Table 7, without taxonomic judgement, as a guide to what to look for and document in furth er explorations of the region.  (Baldwin et al. 2002) . Representative specimens listed can be found at RSA , unless de signated by "paM," "UC," or "JEPS." An as teris k (* ) denotes non-native taxa.                Special thanks go to Kathryn Miller for her patience a nd support th roughout all phases of this project.