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Show 230 Symmetrical clumps of Calamagrostis longifolia 6 feet high, their large panicles bending gracefully outward, send their roots deep down into the dry sand. Kings of Muhlenbergia pungens are scattered over the flats here and there. This grass spreads by underground stems, which grow continually outward, the older inner part dying and disappearing, leaving the bare sand surrounded by a circumference of living green. These centrifugal circles are sometimes 10 feet iu diameter, with the interlaced purple panicles of the ring a foot wide. The rare Oxytenia acerosa, with Bigelovia Wrightii, Heliotropium convolvulaceum, Dicoria Brandegei, An-dropogon Torreyana, are some of the plants common in these dry rivers. When we ride up these rivers of sand, sometimes a bright, green cotton-wood, or Fegundo, is met with, showing that water must be down deep somewhere. How they managed to exist before their roots reached moisture is an interesting question. £ 1 Late and Cariso, groups of low mountains about 9,000 feet in altitude, produce a flora similar to one another and very different from that of the plains from which they rise. Pinus edulis and Juniperus occidentalis cover Cariso, and grow nearly upon the summit of El Late. The characteristic vegetation is the same as that of the La Plata and Animas of the same altitude. Upon the eastern slope of the Kocky Mountains, in the valley of the Arkansas, the Cactacece, on account of their abundance and size, are a prominent part of the vegetation. It was expected that the southern , latitude, low altitude, and dryness of Southwestern Colorado,. with its proximity to the cactus region of Arizona, would be favorable to the growth of Cactacea, but the number of species is less than in the Arkansas Valley, and the number of plants is very small. Only two species to be added to the flora of Colorado make their appearance: an I Echinocactm and a Cylindropuntia. The Cylindropuntia is found at altitudes between 7,000 and 8,000 feet, and Echinocactus WhippUi generally does not grow iu the lowest altitudes, so that the country along the San Juan Biver has not a single additional species of cactus, and lacks very nearly all the species of the eastern slope. The great beds of Opuntia Missouriensis which cover the plains and parks of the eastern slope are not found in Southwestern Colorado; neither Opuntia arborescent nor j Cereus viri& ifloms was seen, and no species is common. The genus Astragalus is represented by few species, and these are not very abundant. They grow almost wholly above 6,000 feet altitude. None of the species of Astragalus of Southwestern Colorado, with the | exception of A. lonchocarpus, appear upon the eastern slope. Twelve leguminous plants were found which grow in Eastern Colorado, while not more than eight species common to the plains of both eastern and western slopes were seen. Few of the Leguminosce are very abundant. The shrubby Rosacea are iu strong force and characteristic of the flora of Southwestern Colorado from high to low altitudes. The species common to both eastern and western slopes, the abundance of some which rarely grow upon the eastern slope, together with those species which here enter the limits of Colorado, give great prominence to the rosaceous shrubs* The genus Eriogonum is well represented iu species, and the plants are very abundant, especially those of the annuals. Nine annual species grow in the San Juan Valley; in the Arkansas Valley but three are found, and in Northern Colorado but one. At about 8,000 feet altitude, the common oak of Colorado is very abundant, growing upon - the bluff- sides and becoming a small tree in moist locations. At lower altitudes, it is rarely seen, and is a small bash |
