FLORA OF THE YELLOWSTONE NATIONAL PARK. 23 



In the moist meadows between 8000 and 9000 feet alt., the 

 following will be found, including several Arctic forms : 



Hierochloa borealis, R. and S. 



Alopecurus occidentalis, Scribn. 



Phleum alpinum, L. 



Agrostis humilis, Vasey. 



Deyeaxia Canadensis, Beauv. 



Deyeuxia Langsdorffii, Kunth. 



Trisetum subspicatum, R. Br., var. molle. Gray. 



Poa re flex a, V. and S. 



Poa nemoralis, L. 



Poa Nevadensis, Yasey. 



Poa alpina, L. 



Poa tenuifolia, Buckl. 



Festuca ovina, L. 



Hordeum nodosum, L. 



As far as observed the only strictly alpine species are Agro- 

 pyrum Scribneri, Vase}^, and Festuca ovina, L., var. brevifolia, 

 Wats., although several of the Poas and others, Poa alpina, P. 

 reflexa, and forms of P. tenuifolia are found above the timber 

 line on exposed ridges and summits. 



Here, as elsewhere in the northwest, one is struck by the great 

 development of the genus Poa, of which at least a dozen species 

 grow within the Park. The great variety of forms are puzzling 

 in the extreme. 



