_Aristida purpurea_ (Western beard-grass; purple "bunch-grass" of Montana).--On the high, rolling prairies of the Missouri-Yellowstone divide this grass is very abundant. It grows in little solitary bunches, about 6 inches high, scattered through the curly buffalo-grass (_Bouteloua oligostachya_). Under more favorable conditions it grows to a height of 12 to 18 inches. It is one of the prettiest grasses of that region, and in the fall and winter its purplish color makes it quite noticeable. The Montana stockmen consider it one of the most valuable grasses of that region for stock of all kinds. Mr. C. M. Jacobs assured me that the buffalo used to be very fond of this grass, and that "wherever this grass grew in abundance there were the best hunting-grounds for the bison." It appears that _Aristida purpurea_ is not sufficiently abundant elsewhere in the Northwest to make it an important food for stock; but Dr. Vesey declares that it is "abundant on the plains of Kansas, New Mexico, and Texas." _Koeleria cristata._--Very generally distributed from Texas and New Mexico to the British Possessions; sand hills and arid soils; mountains, up to 8,000 feet. _Poa tenuifolia_ (blue-grass of the plains and mountains).--A valuable "bunch-grass," widely distributed throughout the great pasture region; grows in all sorts of soils and situations; common in the Yellowstone Park. _Festuca scabrella_ (bunch-grass).--One of the most valuable grasses of Montana and the Northwest generally; often called the "great bunch-grass." It furnishes excellent food for horses and cattle, and is so tall it is cut in large quantities for hay. This is the prevailing species on the foot-hills and mountains generally, up to an altitude of 7,000 feet, where it is succeeded by _Festuca ovina_. _Andropogon provincialis_ (blue stem).--An important species, extending from eastern Kansas and Nebraska to the foot-hills of the Rocky Mountains, and from Northern Texas to the Saskatchewan; common in Montana on alkali flats and bottom lands generally. This and the preceding species were of great value to the buffalo in winter, when the shorter grasses were covered with snow. _Andropogon scoparius_ (bunch grass; broom sedge; wood-grass).--Similar to the preceding in distribution and value, but not nearly so tall. None of the buffalo grasses are found in the mountains. In the mountain regions which have been visited by the buffalo and in the Yellowstone Park, where to-day the only herd remaining in a state of nature is to be found (though not by the man with a gun), the following are the grasses which form all but a small proportion of the ruminant food: _Koeleria cristata_; _Poa tenuifolia_ (Western blue-grass); _Stipa viridula_ (feather-grass); _Stipa comata_; _Agropyrum divergens_; _Agropyrum caninum_.