SUNFLOWER FAMILY 461 
Plants without spreading spines; flowers and involucral bracts normally 4 
Primary leaves foliaceous, sometimes minutely ——— -tipped, noe appressed ; igele: i gene, closely, 
and generally permanently white-tomentose . T. canescens. 
Primary Jars appressed, weakly spinescent, weateele foliaceous; herbage thinly tomentlon or finally 
gl te 2. labrate. 
Plants with most or “a of the primary leaves modified into rigid spreading spines; ams! hea involucral 
Tomentum of the twigs of the season borne in well-defined longitudinal sips that are separated by 
be hag Sten ile achenes glabrous; spines pointing forward, only —. an angle 
of 30-60° with the T. argyraea. 
Tomentum of the twigs of ne season uniformly or nearly vaitecee ri ag ong - separated into lines; 
achenes more or less canescent; spines spreading a wide o the 
P 
Achenes provided with numerous very long hairs paver nearly i socom oe and almost Saineal the pappus- 
bristles; involucral hob 5—6 and flowers 5-9, ept in for 
Heads borne in term nal inflorescences; leav pra eakly or scarcely s 5. comosa. 
Heads axillary to = e primary errs panei aa the ‘maker primary leases transformed ee Bo 
spreading or see spin . T. spin 
1. Tetradymia canéscens DC. Spineless Horsebrush. Fig. 5805. 
Lefredyane canescens DC. Prod. 6: 440. 1837. 
Nutt. Trans. Amer. Phil. Soc. IT. 7: 415. 1841. 
Trtridventa canescens var. inermis A. Gray, Bot. Calif. 1: 408. 1876. 
Una much-branched shrubs mostly 2-6 dm. tall. Leaves, involucres, and twigs con- 
spicuously pe closely white-tomentose; primary leaves linear or oblanceolate, 1-3 cm. long, 
: : i : 
mm , nutely spinulose-tipped and sometimes bearing axillary fascicles of 
shorter and proportionat y broader pbc ao in small cymose se ters terminating 
numerous short nches : involucre 7-10 mm. high, of 4 or reputedly sometimes ; flowers 
41 head ; enes eet ed ut the hairs not reupentiele ione: and not obscuring the 
well-developed fee copio 
ry open places in ay ree he ie plains southe ard extention to moderate elevations in the mountai 
Arid Transition and Canadian Zones; Montana to New o, westward to Briti we Moana p71 in Washington ao 
Oregon east of the Paeeade Mountains, and in California “(eastern slopes of the S a Nevada and of the San 
Bernardino Mountains). Type locality: Columbia River e—Sept. 
env » Bic borders of its range canescens preter has glabrous rather than silky achenes, but 
r to be any correlated differences, and occasional hairy-fruited plants occur through much of 
i area in aie tte fruits are more characteristically glabrous. 
2. Sat ede haae glabrata A. me Little-leaf Horsebrush. Fig. 5806. 
glabrata A. Gray, Pacif. R. Rep. 2: 122. 1854. 
der ers glabrata f. said Puyset; Univ. Wyo ae ity Sci. 1: 107. 1924. 
_ _Abundantly branched ere mostly 3-10 dm. tall; twigs often rather pemney tomentose 
in lines, the herbage otherwise only hil ly and pret ie, tomentose or essentially glabrous. 
Primary leaves more or less joecel age ie tending to be weakly spinescent, 6-10 
: - : : eer ae 
oO Be rs 
-10 mm. high, of 4 or reputedly sometimes 5 thin-margined bracts ; flow 
achenes densely hairy but the hairs not excessively long and not obscuring vi gaat Seed and 
copious p cele 
en Glance in the foothills and plains, Upper Sonoran and Transition Zones; on Oregon and 
Edit “faae to Utah, southward along the east side of the Cascade Mountains and Sie Nevada to 
the Mojave Desert and the Tahachapi Mountains. Type locality: Sierra Nevada. Mar Jar: 
5803. Erechtites prenanthoides 5804. Peucephyllum schottii 
