104 Wyojning' Experiment Station. 



V/halen Canon, July 18, 1894 (No. 525); Cummins, July 30, 1895 

 (No. 1545). 

 Potentilla Plattensis, T. & G. Fl. i, 439 (1838). 



On sandy flats bordering on streams. 



Horse Creek. June 9, 1894 (No. 206); Laramie River, June 19, 

 1894 (No. 2(i5). 

 Potentilla pinnatisecta, n. sp. 



This form should not have been suppressed. In Watson's King's 

 Report it appears as P. diversifolia pintiatisecta. The points upon 

 which he based the variety are well taken but not strongly enough 

 emphasized. The following, it seems to me, justify the separation 

 of this form from P. Plattensis as a distinct species. P. Plattetisis 

 has been repeatedly observed but only on bottom lands near 

 streams and, I think, thus far, with one exception,* only on streams 

 tributary to the Platte. P. ptntiatisecta is strictly alpine. The speci- 

 mens before me were collected on the naked summits of the Medi- 

 cine Bow Mountains, above timber line at about 11,500 feet, grow- 

 ing among the rocks in the. most bleak and barren places. 



The two differ markedly in habit as well as in habitat. P. Platt- 

 ensis is decumbent at base, with branches diffuse or loosely spread- 

 ing. P. pinnatisecta, whWe lis hvSiX\c\ies are slightly decumbent at 

 base, yet the plant as a whole may be spoken of as strictly erect. 

 The cymes are more regular and more open. The leaves are 

 longer, leaflets less crowded and inclined to be pedately parted 

 rather than pinately, strictly cuneate at base. Leaves largely rad- 

 ical, those on the stem greatly reduced. Petioles and stems nearly 

 glabrous with a brownish glaucus hue. Leaves glabrous on the 

 upper surface, softly silky villous on the lower. The plant 5-8 inches 

 high. 

 Potentilla supina, Michx. Fl. Bor. Am. i, 304(1803), P. paradoxa, 

 Nutt. 



Not of frequent occurrence; Hartville, July 16, 1894 (No. 555); 

 Cummins, July 28, 1895 (No. 1525), 

 Sibbaldia procumbens, L. Sp. PI. 284 (1753). 



Frequent at high altitudes, 10,000 ft. and upward. Union Peak, 

 August 13, 1894 (No. 1010); La Plata Mines, August 23, 1895 (No. 

 1799). 



*Bot. Death Valley Exped. Comrib. Natl. Herb, iv, 112 (1893. 



