1920] PALMER, LIGNEOUS FLORA OF THE STAKED PLAINS 93 



with wide-spreading branches close to the ground the better to resist the 

 constant buffeting of the dry winds. Owing to the generally light rainfall 

 and rapid evaporation the subsoil contains little moisture and this condi- 

 tion, together with the great depth of ground water, offers little incentive to 

 deep-rooted plants, those having wide-spreading, shallow root systems being 

 the prevailing types. Ligneous plants are almost entirely absent. Occa- 

 sional stunted bushes of Mesquite and the low Cat's Claw {Mimosa borealis) 

 or the shrubby Senecio may sometimes be found along the slight depressions 



of stream beds and ravines. 



The Mesquite {Prosopis glandulosa) , which is the most frequent woody 

 species, is here strictly shrubby, seldom attaining a height of more than one 

 or two metres. This plant, which makes a small tree under favorable con- 

 ditions, with a maximum height of twelve or fifteen metres and a trunk diam- 

 eter of four or five decimetres, is everywhere in this region the most hardy 

 pioneer of advancing forestation. It has extended its range from its original 

 home, probably south of the Rio Grande, until it now occupies all of the 

 lowlands of the Rio Grande plain, the lower open canyons of the Edwards 

 Plateau and those of the Staked Plains, encircling these tablelands and 

 extending westward through the canyons and river valleys of New Mexico 

 and Arizona and northward into western Oklahoma. Scattered specimens 

 are found as far north as southwestern Kansas and eastward in Texas to 

 the boundary of Louisiana, As the most abundant and widely distributed 

 ligneous plant over hundreds of square miles it is familiar to all travelers 

 in the Southwest, and numerous accounts of it appear in the literature, both 

 scientific and general, dealing with that part of the country. Over a large 

 part of western Texas it is the only species that attains the size of a tree and 

 it is therefore of the greatest value to the ranchers and settlers in the con- 

 struction of fences as well as for fuel and other purposes. The wood is of 

 rapid growth and rather durable; the beans and foliage are eagerly eaten by 

 stock and furnish a valuable addition to the forage at times when grass and 

 other herbage is dried up. Although the thin foliage affords but indifferent 

 protection from the scorching summer sun, as the only refuge, often, in a 

 dry, hot land its shade is most grateful both to man and beast. The testi- 

 mony of travelers and early settlers in western Texas agrees that Mesquite 



was absent or rare not may decades ago in much of the region where it is 

 now so abundant. While evidence of this sort must always be received with 

 caution there can be little doubt that it has advanced widely to the north- 

 ward and eastward in recent years and that the forward movement is still 

 going on with undiminished rapidity. One of the stories told of its introduc- 

 tion into Texas is as follows: 



At an early day in the history of the territory when the Franciscan 

 padres were establishing missions in the San Antonio country and zeal- 

 ously striving, under the banner of the cross, to bestow the blessings of the 

 true faith upon the benighted natives, while Spanish adventurers from 

 Mexico were seeking no less assiduously, by argument of the sword, to sep- 

 arate them from their more material possessions and to locate the fabulous 



