EUPHORBIA, SECTION TITHYMALUS. 105 
Var. COLORADENSIS Nn. var. 
Somewhat intermediate between var. atrosemina and var. 
Missouriensis; characterized especially by the elliptical 
floral leaves. — Mountains of Colorado, Wyoming and 
Utah. — Plate 19. 
The specimens grouped here are much varied and _per- 
haps with better specimens and more material it will be 
possible to make a better disposal of them. Jones, Clear 
Creek Cafion, Col., 239, 1878, and Parry, Rocky Mts., 
1862, are typical. Others are: Watson, Antelope Island, 
Utah, 1880, 1869 (a desert form); Hall, 40°, Col., 1868; 
Cowen, Larimer Co., Col., 454, 1895; Greene, Golden, 
Col., 362, 1870. Pammel & Stanton, Sheridan, Wyo., 
1897, approaches #. dictyosperma. Vasey, Colorado, 
514, 1868, has nearly the seed of var. atrosemina, but has 
several stems 2 to 2.5 dm. high and covered with broad, 
spatulate leaves. A specimen in the National Herbarium, 
probably of the same collection, is similar, but more robust 
and resembles /’. obtusata, though without seed. 
Var. ATROSEMINA D. Var. 
Low, 10 to 15 em. high, branched from the base and 
along the short stem, obconical in outline; leaves thick, 
glaucous; involucre almost glabrous; bracts small; capsule 
with a few short warts on the upper part of the cocci; 
seeds very dark brown, closely wrinkled with broken 
irregular ridges. — From Wyoming, south in the moun- 
tains to Arizona and New Mexico. — Plate 20. 
Specimens examined from Arizona (Pringle, Santa Rita Mts., 1884; 
Wooton, Concho, 80, 1892; Toumey, Bradshaw Mts., 253, 1892; Rusby, 
Prescott, 821, 1883); Colorado (Eastwood, Denver, Platte River, 1892, 
and Grand Junction; Brandegee, Cafion City, 1877, Soda Springs, 550, 
1877; Hall & Harbour, 510, 1862, the same from seed at Athens, Ill, is 
talland open); Wyoming (Nelson, Mexican Mines, 581, 1894). 
E. Mexicana (Engelm.) n. comb. £. multicaulis 
Engelm. Mex. Bound. 21:191. 1859; Boiss. DC. 
Prod. 157: 185. 1862. (not Thuillier, Fl. Paris 
21 
