Promising introduced species.
In 1934 expeditions were despatched to Turkey, Turkestan and China to obtain species of plants likely to be of value in arid areas. Many species have now been tested under American conditions and an evaluation of them is therefore possible. Aristida pennata, obtained from the Kara Kum desert, shows promise as a sand-binder in Arizona since it is able to withstand very hot weather. Carex physoides produces abundant grazing on sand dunes in Asia, but it has not established itself well in America under field conditions. Other species showing promise for sandy situations are Calligonum caput-medusae, Lycium ruthenium, Agriophyllum latifolium, Astragalus confirmans and Agropyron intermedium[Elymus hispidus]. Two forms of Agropyron sibiricum, one glabrous, the other pubescent, were found growing in sandy soil, containing humus, in Turkestan. The pubescent form grows with Artemisia maritima while the glabrous form is found with Artemisia arenaria; both of these Artemisia species are palatable to livestock. In similar situations Poa bulbosa provides winter keep while Agropyron sibiricum, Stipa capillata and S. sareptena furnish spring, summer and autumn grazing. On heavier alkali soils, Aeluropus littoralis, Andropogon ischaemum, A. caricosus, A. intermedius and A. trichophorum show promise. Pennisetum orientale and Erianthus ravennae are doing especially well on the adobe soils of Arizona. Grasses which are of value in erosion control are Poa bulbosa, Hordeum bulbosum, Elymus giganteus and E. arenarius while legumes which have shown promise under American conditions are Astragalus homosus, A. chinensis and Medicago lupulina (the wild alfalfa from Turkestan). Other species are listed which have been under trial at Cheyenne, Wyoming and Mandan, North Dakota, and the belief is expressed that many plants which do not appear promising at present will prove of value in other regions later.-J.H.W.