Purshia

Cowania is united with Purshia in the California Jepson Manual (Thomas Rosatti,1993) and in the Intermountain Flora (Cronquist, N. H. Holmgren & P. K. Holmgren, 1997). The arguments for this seem to be based on reported hybridization between Cowania stansburiana and Purshia glandulosa and P. tridentata. In the Jepson Manual, Purshia glandulosa is further reduced to a variety of P. tridentata. This would seem to make sense if one unites the two genera; however, Cowania has been recognized for the plumose camaretae (multiple fruit), in contrast to the short usually pubescent (in California) camara (simple fruit) of Purshia tridentata. Additionally, there are also questionable reports of hybridization involving another monotypic genus, distinguished by plumose achenetae, Fallugia paradoxa, which has reportedly hybridized with Purshia glandulosa. Thus, one might combine Fallugia with Purshia.

The problem in combining the two genera—Cowania with Purshia—is that Purshia tridentata includes a wide range of easily recognizable ecotypes that have distinct morphologies worthy of taxonomic status. Some examples are shown below with proposed new varietal names. One example is a low shrub with many ascending reddish branches arising from the base that is a common associate of the ponderosa pine belt over extensive areas, from the Sierra Nevada and Cascade Regions (e.g., Spjut 14810, 16050) to the Rocky Mountains in Colorado, New Mexico and Wyoming. A nearly prostrate (krummholtz) type occurs along the eastern slopes of the southern Sierra Nevada at the upper limits of the desert scrub to Wyoming. At the other extreme are arborescent forms that are distinct for the short spur branches with terminal flowers, the plant often with a bonsai appearance (e.g., Spjut 14816, 16049); they are common in the Great Basin Desert from eastern California to Oregon and across Nevada and are also found in the Garry oak woodland of northern California to Oregon. Then there are the less unique or intermediate bush types that are also common in the Great Basin Desert, where in the southern range P.. tridentata appears difficult to separate from Purshia glandulosa that supposedly differs by the more glandular foliage. These variants all seem to show little difference in phenology, except perhaps flowers appear before and with the leaves in some cases. Other differences appear to be ther differen

If Purshia tridentata were to be spilt up into many species or varieties, then it would be preferable that the two genera be kept distinct. Purshia glandulosa and Cowania stansburiana are also quite variable in development of stipitate and impressed glands. Samples of P. tridentata from Washington and California screened by Purdue University for antitumor agents have shown activity only from the ecotype that occurs in the ponderosa pine region of California (collected by Spjut near Mt. Shasta the late 1980's; C-j. Chang, pers. comm.), while another sample collected by A. S. Barclay from the same geographic site—25 years earlier (July 1962), had also shown antitumor activity (USDA ARS Plant Active Books, special collections at NAL). A more detailed study of the genera is needed.

The type for Purshia tridentata was reportedly collected from “prairies of the Rocky Mountains” in Montana (Abrams 1944, Illus. Fl. Pac. States II: 451) as further detailed in the Intermountain Flora (IIIA, 1997; see also Reveal http://128.8.90.214/emeritus/reveal/pbio/LnC/LnCpublic7.html) and links to photos of the types at other institution provided below.

Below are tentative species and varieties distinguished as follows:

1. Fruit a camaretum, usually with 5 or more camaras, each with a distinct persistent long hairy (lanate) style............	*Cowania*
1. Fruit often a camara, or a camaretum with 2 or 3 camaras (especially plants in the Rocky Mountains), the camara gradually tapered to a relatively short persistent style, the style hairs nearly absent, mostly hirsute to pilose on the camara, sometimes glandular.........	Purshia—2
2. Mature leaves strongly revolute—to near the mid region of the leaf, appearing mostly green below; a species primarily found in the Mojave Desert, from the southern part of the eastern Sierra Nevada (S half of Inyo Co.) to southwestern UT and northwestern AZ...	Purshia glandulosa
2. Mature leaves revolute along margins, the lower surface exposed, often appearing densely white tomentose between the margins; a characteristic species of the Great Basin Desert, from desert slopes of eastern and southern Sierra Nevada to the Rocky Mts and Black Hills of SD...	Purshia tridentata
Suggested Varieties for P. tridentata (likely to be revised) 2a. Erect, arborescent shrub to 7 m or more; leaves often in clusters on branched spur shoots; common in sagebrush desert, sometimes in pure stands, occasional in Garry oak woodland, generally east of the Sierra Nevada, along California-Nevada state line from Mono Co. to OR and to western UT (includes calcarata under study)......	ERECTA
2a. Much-branched shrubs, leaves few on mostly simple spur-like shoots, or leaves sessile.....	2b
2b. Low spreading shrubs, generally less than 1 m high, branches wide spreading from near base, slender, not notably rigid; often the most common understory shrub in ponderosa pine, Jeffrey pine and lodgepole pine forest communities, Sierra Nevada from Mono Co. northwards, and Cascade regions in California, east to the Rocky Mts (where plants are commonly found with multiple fruits—camaratae).	GRACILIS
2b. Multi-stemmed, much-branched shrubs, generally 1–2 m high; sagebrush desert communities	2c
2c Twigs reddish, rigid; sagebrush desert, margins of scrub vegetation, especially along roads	RUBICAULA
2c Twigs gray	2d
2d. Leaves with pustulate or sunken glands along margins; rocky sagebrush deserts, eastern Sierra Nevada to northern NV	under study
2d. Leaves glabrous or sparsely white hairy or pubescent above; widely distributed in sagebrush desert	var. tridentata

Cowania ericifolia Black Gap Wildlife Refuge, TX Spjut & Marin 15092 Nov. 2002	* Cowania stansburyana Mojave Desert, Clark Mt., CA Spjut & Marin 14725 May 2002	Cowania stansburyana Mojave Desert, Sandy Springs Rd Clark Co., NV Apr 2005, May 2006
Cowania stansburyana Mojave Desert, Lovell Canyon Clark Co., NV, May 2006	Cowania stansburyana Mojave Desert, Mesquite Mts., CA, May 2006	Cowania stansburyana Mojave Desert, White Mts., Cerro Gordo, 8000 ft., CA, June 2007
Cowania stansburyana Arizona: near Utah state-line, west of Fredonia, Sep 2007.	Cowania stansburyana-Artemisia tridentata woodland Utah: E of Fillmore just W of boundary with Fishlake NF, Sep 2007.
Purshia glandulosa Inyo Co., CA, White Mts., Gilbert Pass along Hwy 266, 6400 ft, arborescent form, Spjut 16081, June 2007. The habit of this plant is much like Cowania stansburyana. It occurs with the shrub form shown on right, 16080. The leaves of this tree form develop on spur shoots similar to what is also seen in P. tridentata var. erecta; there are no glandular twigs evident.	Purshia glandulosa Inyo Co., CA, White Mts., Gilbert Pass along Hwy 266, 6400 ft, shrub form, Spjut 16080, June 2007. Here the leaves are sessile along glandular twigs. Both tree and shrub forms here have sessile glands on the hypanthium, in contrast to stipitate glands seen in P. tridentata.	Purshia glandulosa Kern Co., CA, just W of Walker Pass along Hwy 178; Spjut 16053; Oct 2006 Note: reddish glabrous twigs (not glandular) with short spur shoots and with leaves that have conspicuous sessile oil glands and that are also glandular punctate.
Purshia glandulosa NV: Esmeralda Co., Lida Summit, 7400 ft (2255 m) June 2007. Hypanthium pubescent and with sessile glands.	Purshia glandulosa CA: Inyo Co., White Mts., Westgard Pass, 7200 ft, Spjut 16082, June 2007. Note the short white hairy hypanthium that lacks sessile glands, which are evident in the specimens shown for another site, just to the east, Gilbert Pass (16080-81).	Purshia glandulosa Clark Mt., CA Spjut & Marin 14721 Apr 2002. Leaves with sessile transparent glands along margins and on adaxial surface of lobes. Some flowers have two pistils.
Purshia tridentata E Sierra Nevada, Mono Co., W of Sherwin Summit, CA, Oct 2006 Sessile translucent glands evident along leaf margins and on adaxial surface of leaf lobes, but revised identification based on the lower surface of leaves appearing less revolute and with white tomentum.	Purshia glandulosa CA: Inyo Co., E Sierra Nevada, above Alabama Hills, ~6500 ft, Spjut 16083, June 2007 The upper left photo shows two growth forms, an upright form (16083) and a prostrate form (16084). Could these be different species? The sepals in the above plant (16083) appear relatively short, shorter than the hypanthium, and deltoid in shape, compared to longer somewhat reflexed spatulate sepals in 16084 (photos to the right). Hypanthium white pubescent, hairs occasionally gland-tipped.	Purshia glandulosa CA: Inyo Co., E Sierra Nevada, above Alabama Hills, 6500–7000 ft, Spjut 16084, June 2007 The above includes prostrate forms that were observed mainly along road margins. The habit may suggest mowed or heavily grazed plants, but this habit had been observed at this site 28 years ago, based on a sample collected for the NCI (Spjut & Russell 5531, NA). A few of the prostrate plants show the P. tridentata leaf form, interpreted here as young growth with no flowers or fruits evident, but twigs are glandular. This variation may also be related to a hybrid swarm. The development of the glandulosa foliage on other stems in other plants at this site is also reminiscent of the pubescent and glabrous forms of Amsonia tomentosa seen in the eastern Mojave Desert except the variation in Purshia here seems more complex.
Purshia glandulosa CA: Inyo Co., E Sierra Nevada, above Alabama Hills, 7000 ft, Spjut 16086, June 2007. Hypanthium white pubescent, glandular punctate, and with few sessile oil glands near base.	Purshia tridentata var. rubicaula (ined.) Mono Co., CA Spjut 14810 Jun 2002 Mono Co., CA Pine forest region between June Lake and Mammoth Lake, Spjut 16050 Sep 2006. Hypanthium glandular stipitate	Purshia tridentata var. erecta (ined.) Gardnerville, NV Spjut 14816 June 2002
Purshia tridentata var. gracilis (ined.) Lake Tahoe, CA Spjut 14817 June 2002	Purshia tridentata var. calcarata (ined.) Mono Co., CA Spjut 14818 June 2002 Mono Co., CA between Virginia Lakes and Mono Lake; Spjut 16049 Sep 2006. Hypanthium glandular stipitate. Purshia forest behind rabbit bush (Ericameria nauseosa), Mono Co., CA, Oct 2006. Leaves with transparent glands long margins, calyx tube not glandular stipitate	Purshia tridentata S Idaho, June 2005
Purshia tridentata Elko Co., NV, June 2005 Note: Leaves with pustulate glands on adaxial surface, and glabrous camara (young fruit).	Purshia tridentata SW Idaho, June 2005	Purshia tridentata Lassen NF, CA, July 2002
Purshia tridentata Lassen NF, Eagle Lake, CA July 2003	Purshia tridentata (var. erecta) Siskiyou Co., NE of Yreka, Garry oak woodland, 2700 ft, CA. May 2006. Top left photo by Susan Spjut who also appears in lower left photo. Calyx glandular stipitate.	Purshia tridentata Mono Co., CA Conway Summit, 8140 ft Oct 2006. Hypanthium glandular stipitate.
Purshia tridentata Shasta Trinity NF, Mt Shasta, McCloud Hwy 89, CA, May 2006	Purshia tridentata Shasta Trinity NF, Mt Shasta, McCloud Hwy 89, CA, Oct 2006. Calyx tube glandular stipitate.	Purshia tridentata Lassen NF, CA, Volcanic Rocks, with Cercocarpus ledifolius, May 2006
Purshia tridentata Mono Co., CA Road to Virginia Lakes, 8500 ft July 2005.	Purshia tridentata Mono Co., CA Spjut 14809 Jun 2002	Purshia tridentata E Sierra Nevada, Inyo Co., Pine Creek, CA Apr 2004 Distinguished by the white pubescence on the abaxial leaf surface. Note: This keys to P. glandulosa in the Intermountain Flora (except for geographical range) by the relatively short leaves, appearing to be from "4.5–12 mm long"). The leaves appear thicker than what is generally seen for P. tridentata, and appear to have resinous glands along the leaf margins.
Purshia tridentata Idaho: near corner of UT and NV, just N of Oakley, Sep 2007. Hypanthium with conspicuous glands.	Purshia tridentata Utah: Fish-lake Natl. For., just E of Fillmore, Sep 2007. Hypanthium lacking conspicuous glands.

Cowania stansburiana Torrey in Stansbury's Report of the, Exploration to the Great Salt Lake, 386, 1852.
Type: Great Salt Lake, Stansbury's Island, Utah, 26 June 1850; holotype at the New York Botanical Garden (NY),
http://207.156.243.8/emuwebnybg/pages/common/imagedisplay.php?irn=31840.
Syn.: Purshia stansburiana (Torrey) Henr., Phytologia 60: 468, Aug. 1986.

Purshia glandulosa: M. K. Curran, Bull. Calif. Acad. Sci. 1(3): 153, 1885. Type: Mohave side of Tehachapi Pass, Kern County, California, U.S.A; May & July 1884. Type specimen undetermined? Note: Other specimens by Curran from the same general locality have included fragments such as that for Tetradymia stenolopis at NY and at GH.

Purshia tridentata (Pursh, Flora Americae Septentrionalis 333, 1814; Tigarea tridentata) De Candolle, Trans. Linn. Soc. London 12: 158, 1817. Type: West of Lewis and Clark Pass, Lewis and Clark Co., Montana, 6 Jul 1806. Lectotype: see Academy of Natural Sciences of Philadelphia,
http://clade.acnatsci.org/mccourt/Lewis%20and%20Clark/flattened%20jpgs%2012_10/185.jpg

Ito H., M. Miyake, E. Nishitani, K. Mori, T. Hatano, T. Okuda, T. Konoshima, M. Takasaki, M. Kozuka, T. Mukainaka, H. Tokuda, H. Nishino and T. Yoshida. 1999. Anti-tumor promoting activity of polyphenols from Cowania mexicana and Coleogyne ramosissima. Cancer Lett. 143(1): 5–13. “Chemical investigation on polyphenol-rich fractions of Cowania mexicana and Coleogyne ramosissima (Rosaceae) which showed significant inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol-13-acetate (TPA), has led to the characterization of 10 compounds including C-glucosidic ellagitannin monomers and dimers from the former plant, and 17 polyphenols including flavonoid glycosides from the latter. The effects of individual components and their analogues with related structures on the TPA-induced EBV-EA activation were then evaluated. Among the compounds isolated from C. mexicana, two C-glucosidic ellagitannins, alienanin B and stenophyllanin A and a nitrile glucoside (lithospermoside), and among the constituents from C. ramosissima, two flavonoid glycosides, isorhamnetin 3-0-beta-D-glucoside and narcissin were revealed to possess strong inhibitory effects on EVB-EA activation, the potencies of which were either comparable to or stronger than that of a green tea polyphenol, (-)-epigallocatechin gallate. These polyphenols except for nitrile glucoside, which was not tested owing to an insufficient amount, were also found to exhibit anti-tumor promoting activity in two-stage mouse skin carcinogenesis using 7,12-dimethylbenz[a]anthracene (DMBA) and TPA.”

Konoshima T, M. Takasaki, M. Kozuka, M. Haruna, K. Ito, J. R. Estes and K. H. Lee. 1993. Constituents of rosaceous plants. I. Structure of new triterpenoids from Cowania mexicana. Chem. Pharm. Bull. (Tokyo) 41(9): 1612–615. In our search for possible anti-tumor-promoters, we carried out an investigation of the leaves and branches of Cowania mexicana D. DON (Rosaceae). Two new cucurbitane type triterpenes, 15-oxo-cucurbitacin F (3) and 15-oxo-23,24-dihydrocucurbitacin F (4), were isolated together with cucurbitacin F (1) and 23,24-dihydrocucurbitacin F (2). These triterpenes were inhibitors of Epstein-Barr virus early antigen activation induced by 12-O-tetradecanoylphorbol-13-acetate, a well-known tumor-promoter. The structures of 3 and 4 were determined from 2D-NMR spectral data and difference NOE experiments.