150 POLYGONACEAB (BUCKWHEAT FAMILY) 



bracts oblong-lanceolate, the latter shortly petiolate: inflorescence a very few- 

 rayed irregularly proliferous umbel: flowers whitish, silky, 4-5 mm. long: 

 achene 4 mm. long. — Colorado to New Mexico and Arizona. 



14. Eriogonum flavum NuU. Fras. Cat. 1813. White-tomentose through- 

 out, 1-2 dm. high; caudex branching, the crowns enlarged and scaly: leaves 

 oblanceolate: umbel of 3-9 rays, often short, but quite regular: involucres 

 turbinate, nearly entire; bracts spatulate, foliaceous: flowers yellow, villous; 

 the segments obovate: stamens and style branches exserted: achene con- 

 stricted at middle, long-villous at the summit. (,E. chloranthum Greene, PI. 

 Baker. 3: 15. 1901; E. polyphyUum Small, Mem. N. Y. Bot. Gard. 1: 119. 

 1900; E. xanthum Small, Bull. Torr. Bot. Club 33: 61. 1906; all of these are 

 reduced subalpine states of E. ■flavum.) — From Nebraska through the Rocky 

 Mountains and far to the northwest. 



15. Eriogonum crassifolium Benth. Trans. Soc. Linn. 17: 408. 1837. 

 ResembUng the foregoing but the caudex more indurated and densely clothed 

 in leaf-bases involved in a wooUy tomentum: leaves broader, mostly elliptic, 

 very white, thick and leathery: umbel shorts-rayed (subcapitate) : flowers 

 yellow, very villous. — Frequent in the more desert areas in the region of the 

 North Platte in Wyoming. 



15a. Eriogonum crassifolium tectum A. Nels. Bot. Gaz. 34: 23. 1902. 

 Merely an extreme form with inordinately protected crowns; the flowers even 

 so involved in wool as to hide the yellow calyx-segments. — Hot sandy banks, 

 Wyoming. 



16. Eriogonum Piperi Greene, Pitt. 3: 263. 1898. Allied to the two fore- 

 going but taller and scape slender: villous rather than tomentose, except on 

 the lower face of the thin elliptic or oblanceolate leaves which are shorter 

 than the slender petioles: bracts narrow and petioled: umbel of 5-8 equal 

 rays: perianth greenish-yellow, hirsute, narrowed to a stipe-like base: 

 achene , villous at apex. — ^From northwestern Wyoming and Montana to 

 Washington. 



17. Eriogonum acaule Nutt. Joum. Acad. Phila. II. 1: 160. 1847. Very 

 dwarf and densely matted, scarcely rising above the surface of the ground: 

 leaves crowded, 4-5 mm. long: pedimcle 1 cm. high, bearing a head of 1-5 

 nearly sessile involucres, each with 5 short erect teeth; bracts small: flowers 

 yellow, abruptly narrowed at base, pubescent: achenes densely villous. — 

 Colorado through Wyoming to Idaho. 



18. Eriogonum lachnogynum Torr. ex Benth. DC. Prodr. 14: 8. 1856. 

 Caespitose and densely tomentose: leaves oblongjanceolate: peduncle slender, 

 2-3 dm. high, sparingly dichotomous above; bracts small: involucres solitary, 

 sessile or long-pedunculate, short-toothed: flowers densely tomentose, yeUow: 

 achene attenuate above, 4 mm. long. (E. tetraneuris Small, 1. c. 52.) — <!olorado 

 and New Mexico. 



19. Eriogonum ovalifolium Nutt. Joum. Acad. Phila. 7: 50. 1834. Low, 

 densely tomentose and caespitose, with a short closely branched caudex: 

 leaves elUptic to orbicular, 7-20 mm. long, petioled: bracts temate, very small, 

 and connate at base: involucres in a single close head, on slender erect pedun- 

 cles 3-15 cm. high, cyUndric-turbinate, more or less strongly 5-6-nerved and 

 with as many erect teeth: flowers yellow: the outer sepals oblong, becoming 

 orbicular; the inner spatulate, often retuse. (£?. orthocaulon Small, 1. c. 53.) — 

 Colorado to Montana and far to the westward. Ours belong mostly to the 

 foUowing variety. 



19a. Eriogonum ovalifolium purpureum (Nutt.) A. Nels. Bot. Gaz. 34: 23. 

 1902. Flowers white, shading to rose-color or passing even into deep pur- 

 ple. — ^Frequent on the open plains and ridges of our range, and westward with 

 the species. 



20. Eriogonum ochroleucum Small, Mem. N. Y. Bot. Gard. 1 : 123. 1900. 

 Tufted perennial with the habit of E. ovalifolium: leaves crowded, densely 

 tomentose, obovate-spatulate, cuneately narrowed into the slender, often 

 twisted petiole: scapes erect, slender, 1-3 dm. high: involucres sessile, in capi- 

 tate clusters, ribbed and with short teeth: flowers numerous, ochroleucous 



