428 BOTANICAL GAZETTE [DECEMBER 
pyrum occidentale Scribn. vars. mollis and vivipara, A. tenerum Vas., 
A. spicatum Pursh, Hordeum jubatum L., and Elymus canadensis L. 
Some others are more scattered, for instance: Andropogon furcatus 
Muehl., Echinochloa crus-galli (L.) Beauv., Muehlenbergia glomerata 
Trin., Lycurus phleoides H. B. K., Setaria glauca L., Bouteloua 
prostrata Lag., Diplachne fascicularis (Lam.) Beauv., Eragrostis major 
Host., etc. 
This grass vegetation in the wooded belts and on the plains con- 
sists mostly of American types, and the very few species that are also 
represented in the Old World are mostly introduced, for instance: 
Echinochloa crus-galli, Digitaria glabra, Setaria glauca, Eragrostts 
major, and Agrostis alba. Calamagrostis Langsdorfii, which I found 
in the spruce zone on Mt. Massive, occurs also in the mountains of 
New England, Canada, Alaska, south to California, and is also an 
inhabitant of Europe and Asia. Poa annua, P. nemoralis, P. pra- 
tensis, and Koeleria cristata, widely distributed species in the Old 
World, especially in the lowlands of the cold temperate zone, are also 
represented in the aspen zone. P. nemoralis is very common an 
varies according to the substratum, whether dry rocks or rich soil, in 
thickets, along streams, etc. ; 
In comparing the geographical distribution of these various 
species of Gramineae which occur in the alpine region, in the 
wooded belts of the mountains, and on the plains, it is noticeable 
that the genera of the alpine flora are more cosmopolitan than those 
of the lower levels. None of the genera of the alpine Gramineae a7 
endemic, and about one-half of the species occur also in the Old 
World (cf. Table III). On the other hand, the presence of arctic 
and circumpolar species is characteristic of the alpine flora, Sper 
which may be regarded as remnants of an old glacial vegetation 
that migrated from the far north; but those endemic in Colorado 
may have developed in the alpine regions of these very mountains. 
Let us now examine the grass vegetation of the alpine eit 
of the Alps of Switzerland, the Pyrenees, the mountains of Norway» 
the Caucasus, and the Himalayas. In these mountains the ae 
that occur in Colorado are found, besides the Phalarideae, of we a 
Hierochloa laxa Br. has been reported from the Himalayas (5000")s 
and Anthoxanthum odoratum L, from Switzerland and the Caucast® 
