Page:Popular Science Monthly Volume 80.djvu/221

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217
THE GREAT AMERICAN DESERT

PSM V80 D221 Dagger weed in fruit.pngFig. 3. The Dagger Weed in Fruit. the development of these netted trails. They are not necessarily always associated with the dagger weed, since they also occur on slopes with bunch-grasses only.

Like the little blue stem, the dagger weed has little value in the region aside from its interesting and important rôle in the life history of the ridges and slopes. Some economic value is attached to it in that it is eaten by cattle to a slight degree. Especially when the plant is in bloom, if the range is rather short, stock frequently strip every juicy flower from the large spike or panicle, sometimes even eating the axis well down among the needle-tipped leaves. I have seen them attack the young capsules when the range is especially short, so that in a closely grazed pasture one seldom finds a single fruit of the species.

Besides the bunch-grasses and the dagger weed there are many other species that occur in greater or lesser frequency in the bunch-grass association. PSM V80 D221 Dagger weed adapting to changing soil level.pngFig. 4. The Dagger Weed may Adjust itself to a Changing Soil Level. The hairlike eragrostis (Eragrostis trichodes) is an important secondary grass of the uplands that frequently shows the bunch-grass habit. So also Indian millet (Oryzopsis cuspidata), and the black grama grass (Bouteloua hirsuta) are quite commonly seen in the intervals between the bunch grasses. In fact there are more than one hundred species of grasses alone in the Sand Hills, many of which are confined to the uplands. Besides the species already mentioned the following are other common associates of the bunch grasses: Annual eriogonum (Eriogonum annuum) which, with its slender, gray flowering stems and conspicuous flat-topped clusters of flowers, occurs as widely