60 Flora of the Palousc Region 



92. ERIOGONUM. 



Annual or perennial aeaulescent or leafy -stemmed herbs or 

 shrubs: stems simple or branched, often tufted: leaves entire, alter- 

 nate, opposite or whorled: flowers small, fascicled, cymose, um- 

 bellate or capitate, subtended by 5-8-toothed or cleft campanulate, 

 top-shaped or almost cylindric involucres: calyx 6-cleft or parted, 

 usually colored; segments equal or the outer ones larger: stamens 

 9: akenes pyramidal, 3-angled, more or less swollen near the base, 

 invested by the calyx-segments or winged. 



Annuals: inflorescence loose, the small umbels scattered along the branches. 



E. VIMINEl'M. 



Perennials. 



Inflorescence loosely dichotomous. E. niveum. 

 Inflorescence umbellate, simple or compound, rather dense. 



Flowers hairy, yellow. E. piperi. 

 Flowers not hairy. 



Basal leaves large, oblong-ovate, cordate. E. composiTum. 



Basal leaves small, oblanceolate. E. heracleoides. 



E. vimineuni Dougl. Annual: stems erect, 15-40 cm. tall, much branched 

 above the base, tomentose below, the branches Jong and slender: leaves com- 

 monly in a single rosette at or near the base, broadly oblong or orbicular, 

 2-4 cm. long, densely tomentose beneath, less so above; petiole slender, 

 about as long as the blade: umbels small, 2-8-flowered, sessile and scattered 

 along the sides of the long branches, or in the forks: involucres narrow, 3-4 

 mm. long, 5-toothed and nerved, glabrous: flowers white or pink, 2 mm. 

 long. In basaltic gravel or sandy soil, along Snake River. 



E. niveum Dougl. Densely white-tomentose throughout: stem tufted 

 from a loose woody caudex, 30-50 cm. tall, loosely several-times forked, the 

 branches in twos or threes, ascending: basal leaves ovate or oblong, obtuse, 

 1-3 cm. long, densely white-woolly on each side, on slender petioles; cauline 

 narrower, nearly sessile, whorled at the forks, the upper reduced: umbels in 

 the forks or on the sides of the branches: involucre short and broad, 4 mm. 

 long, 5-6-toothed, the tips somewhat recurving: flowers white or pinkish, 

 4-5 mm. long. Banks of Snake River in stony soil. 



E. piperi Greene. Densely tufted on a stout woody caudex: stems erect, 

 leafless, tomentose, 10-20 cm. tall: leaves all basal, lanceolate or oblanceolate, 

 acute or obtuse, densely hairy beneath, green and less hairy above, 2-4 cm. 

 long, attenuate into a usually shorter petiole: umbels several-rayed, simple, 

 or contracted into a dense cluster: bracts 3-8, oblanceolate, 2-3 cm. long: 

 involucre short-toothed, villous: flowers yellow, very villous, 5-6 mm. long. 

 Summit of Cedar Mountain. Hardly distinct from E- flavum Nutt. 



E. compositum Dougl. Stems stout, simple, 20-30 cm. tall, glabrous or 

 nearly so: leaves ovate or oblong-ovate, cordate, acute, densely white-woolly 

 beneath, green and less so above, 4-iocm. long, on petioles as long or longer: 

 umbels 6-10-rayed, mostly compound, rather dense: principal bracts linear 

 or oblanceolate; branches very short or 2-4 cm. long: involucres glabrous, 

 deeply 5-lobed, the lobes acute, spreading: flowers white or yellow, glabrous. 

 Rocky places, banks of Snake River. 



