Rydbekg : Rocky Mountain flora 559 



Colorado : New Windsor, 1 898, G. E. Osterlwut 23 (type) ; 

 also Buckhorn Creek, 1897, and Cheyenne Canon, 1895; foot- 

 hills west of Fort Collins, 1893, C. F. Baker. 



Opulaster glabratus sp. nov. 



A shrub about 1 m. high ; bark of the stems gray and flaky, 

 that of the old branches dark brown and of the young shoots yel- 

 lowish or reddish ; petioles 1-2 cm. long ; leaf-blades rounded- 

 ovate, orbicular or sometimes slightly reniform, 2-3 cm. long, 

 glabrous, slightly paler beneath, 3-5-lobed, obtuse ; corymb 

 rather small, glabrous ; bracts small, lanceolate, deciduous ; hy- 

 panthium almost glabrous ; sepals oval or rounded-ovate, obtuse, 

 sparingly stellate beneath, densely so above, about 3 mm. long ; 

 petals rounded-ovate, about 4 mm. long, pink or white ; carpels 

 2, united to above the middle, densely stellate. 



This resembles in habit a small -leaved 0. intermedins, but is 

 closer related to 0. monogynns, differing in the larger, less 

 dissected leaves and the less stellate and larger calyx and 

 hypanthium. The type grew at an altitude of between 3,000- 

 3,800 m. 



Colorado: West Spanish Peaks, 1900, Rydberg & Vreeland 

 602J (type); Turkey Creek, 6026 ; Rist Canon, 1898 and 1899 

 (collectors not given). 



Holodiscus microphyllus sp. nov. 



A low shrub ; bark of the stems dark brown ; that of the 

 branches light, yellowish or brownish, soft-strigose ; leaves spatu- 

 late-cuneate, 1-1.5 or rarely 2 cm. long, evenly serrate, with 

 strong nerves beneath, finely strigose or glabrate above, densely 

 soft-pubescent beneath, at first almost white, in age more glabrate ; 

 inflorescence small, 3-5 cm. long, its branches short and few- 

 flowered ; sepals about 1 mm. long, ovate, as well as the peduncle 

 and pedicels soft-villous ; petals broadly obovate, a little exceed- 

 ing the sepals ; hairs of the carpels copious, about equaling the 

 stamens. 



This has gone under the name of H. dumosus, but the original 

 Spiraea ditmosa Nutt. is a larger plant with large inflorescence and 

 larger incised or doubly toothed leaves, and apparently the same 

 as 5. discolor Pursh. 



Utah: Alta, Wahsatch Mountains, 1879, M. E. Jones 1142 

 (type in herb. Columbia University); Uintahs, 1869, 5. Watson 



