364 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
Penstemon exilifolius desertus A. Nels. Bull. Torrey Club 28: 231. 1901. “On dry 
sandstone ridges * * * Point of Rocks [Wyoming], Jun. 12, 1900 [A. Nelson] 
no. 7160.’ Isotype seen in herbarium of New York Botanical Garden. 
Dry sandstone ridges, at altitudes of 2,100 to 2,400 meters; Submontane Zone; 
flowering from mid-June to early July. Interior low ridges, central and southwestern 
Wyoming and (probably) southeastern Idaho. 
Wyomine: Fremont: Big Sandy (U); Birds Eye, Nelson 9363 (M, U, Y); Camp Stam- 
baugh (U); Wind River Mountains (U). Hot Springs: Owl Creek, Parry 206, 
in 1873 (A, F, Y). Natrona: Bessemer, Goodding 181 (M, U, Y); Garfield Peak 
(R); Platte River Canyon (M). Sweetwater: Leucite Hills (U); Point of Rocks, 
Nelson 4748 (R), 7160 (B, F, M, U, Y), Pennell 5888 (U, Y). 
Ipano: “Snake Country, [a friend of] Tolmie” (Y). 
56. Penstemon ambiguus Torr. 
Penstemon ambiguus Torr. Ann. Lyc. N.Y. 2: 228. 1828. “Hab. Near the Rocky 
Mountains [Z. P. James in 1820].” Type, collected probably in eastern Colorado, 
northeastern New Mexico, or northwestern Texas, seen in herbarium of Columbia 
University at the New York Botanical Garden. 
Leiostemon purpureus Raf. Atl. Journ. 1: 145, 1832. Based upon ‘‘Penstemon 
ambiguum” Torr. 
Penstemon ambiguus foliosus Benth. in DC. Prodr. 10: 321. 1846. ‘In montibus 
Scopulosis (Fremont!). (v. in herb. Torrey.).”” Type, Frémont 623; according to his ~ 
notes, collected “‘On the high level prairie, Jul. 7, 1844,”’ probably in Cheyenne 
County, Colorado; seen in herbarium of Columbia University at the New York 
Botanical Garden. 
Letostemon ambiguus Greene, Leaflets 1: 223. 1906. 
Prairies, at altitudes of 800 to 1,300 meters; Upper Sonoran Zone; flowering from 
mid-June to mid-July. High plains, on both continental slopes, western Oklahoma 
and eastern Colorado to southwestern Utah and Chihuahua. 
CoLorapo: Cheyenne (?): Frémont (Y). Logan: Sterling, Osterhout 990. Otero: 
Rocky Ford, Berg 1836 (Y). Yuma: Wray, Osterhout 3984, 4332 (Y); Yuma. 
Uran: San Juan: Near Bluff, Rydberg & Garrett 9934 (Y). Washington: St. George, 
Palmer 379 (F, Y). 
57. Penstemon deustus Dougl. 
Penstemon deustus Dougl.; Lindl. Bot. Reg. 16: pl. 1818. 1830. ‘P. deustum 
Douglas in herb. Hort. Soc. Native of Northwest America, where it was found by 
Mr. Douglas on scorched, rocky plains, in the interior. Our drawing was made in 
the Garden of the Horticultural Society in September, 1829.” Type not seen or 
verified, but description evidently of plant here considered. 
Dry, rocky soil, at altitudes of 1,500 to 2,200 meters; Submontane Zone; flowering 
from early to late July. Bighorn County, Wyoming to Washington, southward to 
Nevada and northern California. 
Wromina: Bighorn: Worthley 35 (U). Park: “Stinkingwater,’’ Parry 207 (A, F, 
M, Y). Yellowstone National Park: Near Excelsior Geyser (F); Golden Gate, 
Pennell 6029 (D, H, P, 8, Y); Junction Butte (U); Mammoth Hot Springs (F, M, 
U, Y); Obsidian Creek (R); Silver Gate (Y); head of Swan Lake Valley (U); 
divide between Snake River and Yellowstone Lake (U). 
Ipano: Bingham: Big Butte Station, Palmer 481 (U). Bonneville: Idaho Falls, 
Palmer 372 (U). Fremont: Ashton, Pennell 6045 (F, M, R, U, Y); St. Anthony 
U, Y). 
58. Penstemon watsoni A. Gray. 
Penstemon fremontii parryi A. Gray in King, Geol. Expl. 40th Par. 5: 218. 1871. 
“Colorado (Parry). Toyabe, Diamond and East Humboldt Mountains, Nevada; 
