First Report on the Flora of Wyoming. i8i 



Populus monilifera, Ait. Hort Kew. iii, 406 (1789). 



This species is used to some extent for shade purposes. If native 

 in the state I have not yet observed it. 

 Populus tremuloides, Michx. Fl. Bor. Am. ii, 243 (1803). 



The Quaking Asp of the canons and hillsides, usually only a 

 large shrub but in some places attaining considerable size as trees. 

 Laramie Hills, May, 12, 1894 (No. 23); noted in scores of other 

 places. 



HYDROCHARITACE^. 



Elodea Canadensis, Michx. Fl. Bor. Am. i, 20 (1803). Udora Cana- 

 densis, Nutt. 



In the ponds and springs on the Fish Hatchery grounds where it 

 has probably been introduced. October 18, 1893. 



ORCHIDACE^. 



•Calypso borealis, Salisb. Parad. Lond. t. 89 (1807). C. bulbosa, (L.) 

 Oakes. 



This beautiful little Orchid is as rare here as elsewhere. The 

 following students each found one specimen on a partly wooded 

 hillside at the head of Pole Creek. May 25, J 894 (No. 61) : Lily 

 Boyd, Tessie Welch and Ben Bartlett 



Listera convallarioides, (Sw.) Torr. Comp 320 (1826). 



Very rare, only observed once; Centennial Valley, August 17, 

 1895 (No. 1694). 



Spiranthes Romanzoffiana, Cham. Linnsa, iii, 32 (1828). Gyros- 

 tachys Romanzoffiana, (Cham.) MacM. 



Abundant in a few localities; Centennial Valley, August 10, 

 1895 (No. 1663). 

 Habenaria gracilis, (?) Watson. 



The following numbers, (420 and 1706) appear in our herbarium 

 as H. hyperborea, but re-examination shows that they should 

 probably be referred as above. Frequent in marshy places. 



Chugwater Creek, July 7, 1894 ; Centennial Hills, August 17, 

 1895. 



Habenaria hyperborea, R. Br. in Ait. Hort. Kew, Ed. 2, v, 203 (1813). 

 Specimens only from Big Wind River, August 8, 1894 (No. 725). 



