240 ASCLEPIADACE^E. (MILKWEED FAMILY.) 



umbel loosely many-flowered : corolla dull greenish-purple : column as high 

 as broad : hoods flesh-color, erosely truncate and somewhat toothed at the 

 broad summit, hardly exceeding the anthers, shorter than the falcate-subulate 

 incurved horn : anther-wings bicorniculate at base. From Dakota to Texas 

 and eastward across the continent. 



= = Umbels mostly more than one : peduncle not overtopping the leaves, some- 

 times none. 



a. Leaves broad (from orbicular to oblong-lanceolate), large: hoods broad, little 



if at all overtopping the anthers : stems stout, a foot or more in height. 



4. A. Jamesii, Torr. Puberulent when young, soon green and glabrous : 

 leaves about 5 pairs, approximate, very thick and large, orbicular or broadly oval, 

 often emarginate and with a mucro, subcordate at base, nearly sessile, copi- 

 ously transversely veined : umbels 2 or 3, all or mostly lateral, densely many- 

 flowered : flowers greenish : column very short but distinct : hoods barely 

 equalling the anthers, broad, with a truncate entire summit, which is equalled by 

 the upper margin of the falciform triangular crest, the apex of which extends 

 into a short subulate horn partly over the top of the sligmatic disk. Bot. Mex. 

 Bound. 162. Plains of Colorado to Arizona and Texas. 



5. A. arenaria, Torr. Lanuginous-tomentose, in age glabrate : stems 

 thickly leaved : leaves smaller, coriaceous when old, obovate or oval and retuse 

 or the lower ovate, with rounded or subcordate base, somewhat undulate, dis- 

 tinctly petioled : umbels all lateral, rather densely many-flowered : corolla 

 greenish white : column nearly half the length of the anthers : huods about as 

 broad as high, surpassing the anthers, truncate at base and summit, the latter 

 oblique and notched on each side near the inner angle, which forms an obtuse tooth ; 

 horn with included ascending portion or crest broadly semilunate as high as the 

 hood; the abruptly incurved apex subulate-beaked, horizontally exserted, or the 

 slender termination ascending. Bot. Mex. Bound. 162. On sandbanks, 

 S. E. Colorado to New Mexico. 



b. Leaves narrow (lanceolate or linear), green, and nearly glabrous, the veins 

 oblique : stems branching, a span or two high : hoods obtuse : column hardly 

 any : follicles when young tomentose-canescent. 



6. A. brachystephana, Engelm. Stems 6 to 10 inches high, very leafy, 

 cinereous-puberulent or tomentose when young, the inflorescence more floccose- 

 tomentose : leaves from lanceolate with a broader rounded base to linear, 

 short-petioled, very much surpassing the (3 to 8) few-flowered umbels : flowers 

 lurid-purplish : hoods only half the length of the anthers, erect, strongly angulate- 

 toothed at the front ; the tip of the erect subulate horn exserted. Torr. Bot. 

 Mex. Bound. 163. Dry sandy soil, from Wyoming and Colorado to Arizona 

 and Texas. 



7. A. uncialis, E. L. Greene. Stems an inch or two high : flowers like the 

 last, but the hoods only a little shorter than the anthers, the back rounder, and 

 the triangular anterior lobes or auricles not projecting, while a short Jleshy process 

 takes the place of the subulate horn. Bot. Gazette, v. 64. Wyoming, Colo- 

 rado, and New Mexico. 



c. Leaves from ovate to oblong, mostly pubescent or puberulent : stems a foot or 

 more high : hoods obtuse, 2 or 3 times the length of the anthers, not tapering to 



