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Show 229 graceful, bushy tree that the name Green Mesa is due. The pinon is scattered here and there, sometimes covering quite an area, especially where the sandstone does not reach the surface. Very rarely, upon a rocky ledge, is seen a solitary tree of Juniper us Yirginiana. The trails over the Mesa Verde, some of them evidently very old, generally cross the small parks and follow up openings in the juniper- forest. The sage-bash { Artemisia tridentata) covers these parks so thickly that they are almost impassable excepting by the narrow trail, so narrow that as we ride along the encroaching Artemisia is continually brushing against us. The yellow flowers of Eeliantkus petiolaris and lenticularis, of Actinella Torreyana and Richardsonii, the delicate pink blossoms of Mamillaria rivipara, the light blue of Pentstemon linaroides, and the hooked spines of Echinocactus Whipplei sometimes are seen; but, after having crossed the Mesa Verde, one has the impression that its vegetation is all juniper and sage- brush. There is a great difference between the vegetation of the northern slope and canons ( altitude 8,000 feet) and that of the southern edge ( altitude 6,000 feet), due mainly to the lower altitude and smaller rain- fall of the southern portion. The northern portiou is covered with a luxuriant growth of Peraphyllum, Fendlera, Purshia tridentata, Cercocarpus parvifolius, Amelanehier alnifolia, Quercus, and Yucca baccata, while the southern portion has only a growth of Purshia, Cowania} Ephedra, and Fraxinus anomala. The valley of the Safl Juan really comprises the whole extent of country of the southwest explorations; but as the term is applied to the habitat of plants of the collection, it is limited to a district north of the river about twenty miles wide. The San Juan River was followed from the mouth of the Bio La Plata ( 5,300 feet altitude) in Kew Mexico, along its course into Utah, twenty miles from the Colorado line ( 4,300 feet altitude). All plants of the San Juan Valley of New Mexico come into the limits of Colorado about the mouth of the Mancos, where the San Juan barely touches the corner of Colorado. Some of the species seen only in Utah may not enter the limits of Colorado; but their number is small, less than a dozen. The San Juan Valley is even drier than the Mesa Verde; the soil is perfectly dry close up to the water of the river. The bottom- lands are generally less than one mile wide, and produce quite a growth of plants, which send their roots down in the earth to the level of the water of the river. The course of the Bio San Juan can be distinctly seen long before we reach its banks; it is a line of green a mile wide and many miles in length, winding through the gray desert Groves of large cotton wood are scattered along its course, and dense thickets of Shepherdia argentea, Crataegus cocciena, and 8a-lix longifolia line its banks. The fragrance of the Bigelovias and other plants is noticeable at a distance of two or three miles; and as we return in the evening after a ride over the dry, barren plains, the delightful odor filling the air announces the proximity of the river long before we reach it The mesas of the San Juan Valley are very barren of vegetation. The handsome Eriocoma cuspidata is sometimes plenty enough to afford a night's pasturage for the mules, aud, compared with the general scarcity of growth, Pleuraphis Jamesii often seems plenty. There are large areas with absolutely nothing growing upon them, and often, even along the streams, our day's journey would be lengthened four or five miles before grass could be found sufficient for a camping- place. The alkaline flats abound in Chenopodiacew, mainly SarcobatuSj Atriplex Nuttallii and conferti/ olia. Where Mount Elmo and Montezuma Creeks, dry streams from the north, come down to the San Juan, we find many interesting plants. Ko. 3 3 |
