1908] HOLM—ALPINE GRAMINEAE 427 
with some others which are common also to the aspen zone below. 
The following were observed only in the spruce zone: Sporobolus 
brevicalyx Scribn.., Calamagrostis Langsdorfii (Link) Trin., C. 
Scribneri Beal, A grostis humilis Vas., Poa reflexa Vas. and Scribn., 
and Festuca ovina pseudo-ovina; while Poa pratensis L. was also 
collected in the aspen zone. 
If we continue the comparison, and examine the species that occur 
in the aspen zone, we meet with a larger number of species of the same 
tribes that were observed at higher elevations, and with them there 
also occur some of the Chlorideae. Peculiar to this zone are: Stipa 
minor Scribn., M uehlenbergia comata Benth., M. gracilis Trin. and the 
Var. breviaristata Vas., Alopecurus aristulatus Michx., Sporobolus 
depauperatus (Torr.) Scribn., Agrostis exarata Trin., Trisetum 
monianum Vas., Koeleria cristata Pers., Glyceria americana (Torr.), 
G. Holmii Beal, Poa annua L., P. nemoralis L., Festuca Thurberi Vas., 
Bromus breviaristatus Thurb., B. Richardsonis Link, Hordeum no- 
dosum L., Elymus Sitanion Schult., and E. brevifolius (Sm.). Besides 
these there are a few species which occur here, but which more prop- 
erly belong to the plains, where they are more abundant and more 
typically developed. These are Agrostis scabra Willd., Schedon- 
nardus texanus Steud., Bouteloua oligostachya Torr., and Atropis 
Mroides (Nutt.). The number of species of Gramineae observed in 
the mountainous regions, from the aspen zone to the summits, aver- 
ages about 50, among which the Chlorideae are rather scantily repre- 
sented, aoe mis 
Descending to the plains, at an elevation of 1500™ about 4o 
“pecies belonging to the same tribes are found; the Andropogoneae 
and Paniceae are added; and the Chlorideae abound. The follow- 
Ing species are very frequent: Panicum virgatum L., P. capillare L., 
Aristida fasciculata Torr., Stipa comata Trin. and Rupr., S. viridula 
tin., Eriocoma cuspidata Nutt., Cenchrus tribuloides L., Sporobolus 
‘ryptandrus Muehl., S. asperifolius Thurb., S. atroides Torr., Cala- 
movilfa longifolia (Hook.) Hack., Agrostis scabra Willd., A. interme- 
dia Scribn.; A. ‘alba L., Schedonnardus texanus Steud., Bouteloua 
oligostachya Torr., B. racemosa Lag., Buchloé dactyloides Engelm., 
lunroa squarrosa.(Nutt.) Torr., Distichlis spicata (L.) Grne., Atropis 
“roides: (Nutt.), Poa Buckleyana Nash, Festuca tenella Willd., Agro- 
