when any is present, is the common sage brush (Artemisia tridentata). The characteristic undershrub is some form of Bigelovia, indiscriminately called White Sage, Rabbit Brush, Golden Rod, etc. Plains of this character may also be denominated grassy plains. The grasses on these of course vary greatly as to the species and the luxuriance of their growth. The following are among those of most frequent occurrence: Agropyrum glaucum, A. violaceum, Bouteloua oligostachya, and B. racemosa, Buchloa dactyloides, Koeleria cristata, one or two Festucas and several Poas. Along water courses and in boggy places, as well as in over-irrigated places, these are replaced or become mixed with many species of Juncus, Scirpus and Carex. Sometimes Foxtail (Hordeum jubatum) takes complete possession.

The second class.-The plains strongly impregnated with alkali (sodium carbonate or sodium sulphate), are in some instances nearly devoid of vegetation, but more usually we find several characteristic plants. If the alkali be sodium sulphate the characteristic shrub is Sarcobatus vermiculatus, the well-known Grease Wood. On sodium carbonate soil, this, if not replaced by, has mingled with it some form of Atriplex, usually A. confertifolia, frequently called White Sage. Other species of Atriplex, mostly annuals, are found in this character of soil, and if the soil is very strongly impregnated, as on the shores of salt-marshes and partially dried up alkali lakes, the various species of Atriplex, of Sueda and of Salicornea are often the only vegetation. In real alkali bogs we find Distichlis maritima, Triglochin maritima and T. palustre as the most characteristic vegetation.

The other areas may be spoken of as the foot-hills and the mountains.

FLORA OF THE FOOT-HILLS.

Two kinds of foot-hills must be recognized, viz: wooded and denuded. The denuded slopes are of course much dryer and a large part of the year devoid of all streams. These foot-hills, if stony or gravelly, are covered with Cercocarpus parvifolius, Rhus tridentata, Amelanchier alnifolia, Purshia tridentata-one or more in varying proportion. The intervening valleys, if soil is fertile, are usually covered with sage brush. The herbaceous vegetation in such foot-hills is so varied that no list can be offered here, but the following genera are well represented: Draba, Astragalus, Potentilla, Actinella, Erigeron, Senecio, Krynitzkia, Phlox, Penstemon, and Poa.

If the soil contains alkali, the above-mentioned shrubs give place to Grease Wood, and the herbaceous vegetation largely disappears.

The wooded foot-hills are less common, but they occur at intervals in the Laramie range, much more frequently in the Medicine Bow Mountains and the Wind River range. The arboreal vegetation consists of only a few species, unless one includes the Willows that skirt most of the streams that flow from the higher mountains. Lodge Pole Pine, Douglas Spruce, Rocky Mountain White Pine, Black Cottonwood (Populus angustifolia) and more rarely Blue Spruce, Engelmann's Spruce and Rydberg's Cottonwood (Populus acuminata) are the most frequently met with. The shrubs are more varied and include, besides those mentioned for the drier hills, Junip erus, Prunus, Willows and Quaking Asp. The latter in some places becomes a small tree and is in fact found at all altitudes along streams or on hill-sides below snow

banks. The smaller vegetation likewise includes a much greater number of species, each of which apparently strives for the mastery and produces the most beautiful confusion of forms.

THE MOUNTAIN FLORA.

Some of the mountain ranges are quite heavily timbered, notably the Medicine Bow and Wind River ranges. The Laramie Mountains are wooded only in part and some of these areas very sparsely. Other ranges are known to be wooded, but I speak only of those I have visited. The summits of the Laramie Mountains are mostly rounded and undulating, and on these we find a scattering growth of Rocky Mountain Yellow Pine (Pinus ponderosa scopulorum) and occasionally some straggling, stunted specimens of the Virginia Juniper. Wherever we find the range broken by more abrupt slopes, deeper canons and water courses, the arboreal vegetation assumes the character of a forest, and in some districts furnishes valuable lumber. This is the case at Laramie Peak and on some of the spurs that run out from it. The forests consist mostly of Douglas Spruce, Rocky Mountain White Pine and Lodge Pole Pine.

Much the larger part of the Medicine Bow Mountains are heavily wooded, and it is from these forests that the larger part of the native lumber used in the southern part of the state is obtained. About the same species prevail as in the Laramie Mountains, with the addition of the Blue Spruce and Engelmann's Spruce. The White Pine (Pinus flexilius) and Douglas Spruce form much the larger part of the whole. The latter, along the streams at the foot of the ranges, reaches its greatest size and it grad

ually comes to form a larger proportion of the whole until at 9,000 feet and upward it constitutes practically an unbroken forest to the exclusion of other species. At timber line it becomes scattering, dwarfed and depressed, spreading out like a huge mat under the enormous pressure of the winter snows.

Practically the same conditions prevail in the Wind River Mountains, and probably, though I cannot speak from observation, in the Big Horn Mountains.

Of the fruticose and herbaceous vegetation I need not speak here, although the summits of these ranges yield many beautiful and strictly alpine forms. These all receive comment in their proper place in the list, so space may not be consumed for that purpose here.

THE TREES OF THE STATE.

A list of the trees of the state is indeed very short and were those on the border line between trees and shrubs excluded in would be shorter yet by a third.

Rocky Mountain Yellow Pine (Pinus ponderosa scopulorum).
Rocky Mountain White Pine (Pinus flexilis).

Lodge Pole Pine (Pinus Murrayana).
Engelmann's Spruce (Picea Engelmanni).
Blue Spruce (Picea pungens).

Douglas Spruce (Pseudotsuga Douglasii).
Virginia Juniper (Juniperus Virginiana).
Black Cottonwood (Populus angustifolia).
Rydberg's Cottonwood (Populus acuminata).
Quaking Asp, Aspen (Populus tremuloides).
Willow (Salix longifolia).

Willow (Salix flavescens).

Willow (Salix amygdaloides).
Willow (Salix lasiandra).
Green Ash (Fraxinus viridis).

Box Elder (Negundo aceroides).

Scrub Oak (Quercus undulata)
Wild Plum (Prunus Americana).
Wild Cherry (Prunus demissd).
Wild Cherry (Prunus Virginiana).
Hawthorn (Cratægus rivularis).
Hawthorn (Crataegus Douglasii).
Service Berry (Amelanchier alnifolia).
(Eleagnus argentea).

Buffalo Berry (Shepherdia argentea).
Black Birch (Betula occidentalis).
Black Alder (Alnus incana virescens).
Sage Brush (Artemisia tridentata).

In a few localities of the state occasional specimens of Sage Brush attain a remarkable size-small trees in fact -so that a man on horseback may ride erect underneath the branches.

Other species have been reported but until the specimens are at hand they will not be listed. The number of shrubby plants is so great that to list them separately would be to reprint a large part of the succeeding systematic list.

THE FLORAS OF THE PACIFIC AND THE ATLANTIC

SLOPES.

I have had no opportunity to compare the floras of the two regions except in so far as the plants on the western side of the Wind River range and those of Jackson's Hole and the Tetons, all of which are on the Pacific slope, may be compared with those on the eastern side of the Wind River Mountains and those of the south-eastern part of the state, which represent the Atlantic slope. Such examination has led to the conclusion that the continental divide, though dividing the waters, does not separate floras. The two regions have a 'far larger number