130 POLYGON ACE AE (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 Nutt. 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. polyphyllum Small, Mem. N. Y. Bot. Card. 1: 119. 

 1900; E. xanthum Small, Bull. Torr. Bot. Club 33: 51. 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. 

 Resembling the foregoing but the caudex more indurated and densely clothed 

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

 very white, thick and leathery: umbel short-rayed (fcbcapitate) : 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 Pi peri 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. Journ. 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: peduncle 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 oblong-lanceolate: peduncle slender, 

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

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

 achens attenuate above, 4 mm. long. (E. tetraneuris Small, 1. c. 52.) Colorado 

 and New Mexico. 



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

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

 leaves elliptic to orbicular, 7-20 mm. long, petioled: bracts ternate, very small, 

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

 cles 3-15 cm. high, cylindric-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. (E. orthocaulon Small, 1. c. 53.) 

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

 following 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, 



