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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 Virginiana. The trails 

 over the Mesa Yerde, some of them evidently very old, generally cross 

 the small parks and follow up openings in the juniper-forest. The sage- 

 bush (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 Helianthuspetiolaris and lenticularis, of Actinella 

 Torreyana and EicTiardsonu , the delicate pink blossoms of Mamittana 

 rivipara, the light blue of Pentstemon Unaroides, and the hooked spines 

 of Echinocactus Whipplei sometimes are seen ; but, after having crossed 

 the Mesa Yerde, one has the impression that its vegetation is all jumper 

 and sage-brush. There is a great difference between the vegetation of 

 the northern slope and caiions (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 portion is covered 

 with a luxuriant growth of Perapliyllum, Fendlera, Pursliia tridentata, 

 Cercocarpus parvifoliu*, Amelanchier alnifolia, Quercus, and Yucca baccata, 

 while the southern portion has only a growth of Purskia, Coicania, 

 Epliedra, and Fraxinm anomala. 



The valley of the San Juan really comprises the whole extent of coun- 

 try 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 Rio La Plata (5,300 feet altitude) in Xew Mexico, along 

 its course into Utah, twenty miles from the Colorado line (4.300 feet al- 

 titude). All plants of the San Juan Yalley 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 Yalley is even drier than the 

 Mesa Yerde ; the soil is perfectly dry close up to the water of the river. 

 The bottom-lauds 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 Rio 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 Slieplierdia argentea, Cratcegus cocciena, and Sa- 

 Ux 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 delight- 

 ful odor filling the air announces the proximity of the river long 

 before we reach it. The mesas of the San Juan Yalley are very barren 

 of vegetation. The handsome Eriocoma cuspidata is sometimes plenty 

 enough to afford a night ? s pasturage for the mules, and, 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 Ckenopodiaetttj mainly 

 Sarcdbatus, Atriplex Suttallu and covfertifoUa. 



Where Mount Elmo and Moutezuma Creeks, dry streams from the 

 north, come down to the San Juan, we find many interesting plants. 

 Xo. 3 3 



