Distribution and movements of desert plants (Google eBook)

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Carnegie Institution of Washington, 1909 - Botany - 144 pages
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Page 144 - RUTHVEN, AG 1907. A collection of reptiles and amphibians from southern New Mexico and Arizona.
Page 11 - ... need these at the price, and more arid areas would be better off in the long run in open grass pastures. Where mesquite is accompanied by prickly pear or other thorny species, as it is to the southeast of San Antonio, it becomes a serious menace to grazing interests and a heavy expense to farmers. This encroachment of mesquite is partially accounted for by its weedlike capacity for occupying new ground, its preference for the flat country and compact soils characteristic of the grass prairies,...
Page 143 - CAMERON, FK, and GALLAGHER, FE 1908. Moisture content and physical condition of soils. US Dept. Agr.
Page 104 - ... the suf frutescent and woody forms; or else their growth is completed within the course of a few weeks, or at most a few months, during those portions of the year when mesophytic conditions prevail to some extent over the country. There appears to be little middle ground in this matter».
Page 8 - ... involved are, however, not in all cases clear. Among the examples cited by Steward (1953, p. 46) are mesquite in the southern plains, sagebrush in Colorado and Wyoming, and deciduous trees in the grassland of Canada. The spread of mesquite, according to Bray (1904, p. 34; 1906; see also Cook, 1908), ". . .northward and eastward from the Rio Grande country during the past 50 years has been a marked phenomenon. By its invasion, mile after mile of treeless plain and prairie have been won and reduced...
Page 3 - ... turbidity of the stream, and the long period when no water appears above ground, are not conducive to the normal development of water-plants. Yet there are places where these do secure a foothold and grow with remarkable vigor. Especially is this true of the irrigating ditches, in which green algte frequently accumulate in such quantities that they have to be cleaned out to prevent the channels from becoming choked. Great masses of Cladophora are often thrown out on the banks for long distances....
Page 20 - ... intensity. It ventures here and there a little beyond the shade, and though strikingly modified in form and structure by exposure to full insolation for a part of the day, it is nevertheless capable in this situation of maturing its seeds. It is apparently a plant of essentially the same physiological requirements as the so-called shade-loving species of mesophytic forests, and in the one case as in the other it may well be questioned whether, in the complex of physical factors necessarily involved,...
Page 144 - Biological relations of desert shrubs. II. Absorption of water by leaves. Bot. Gaz., 41: 262-282.
Page 27 - Among later arrivals are the alfilaria (Erodium cicutarium) and foxtail (Hordeum murinum), both of which have made themselves at home, and their presence is materially felt over wide areas. The physiological requirements of these and numerous other species introduced here, as well as their distribution in relation to local conditions, are, to all appearances, much the same as in the different regions from which they came, but it is noteworthy that they exhibit comparative indifference to intense...
Page 71 - Ransome, FL, The geology and ore deposits of the Bisbee quadrangle, Arizona: Prof.

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