Plant Life in the Mexican Arid Regions 



By Elmer Stearns. 



The plant life in this region is a good example of the 

 '•survival of the fittest." The spiny plants and trees 

 so common here did not become spinous by chance, 

 but in each generation it was the one that was the best 

 protected by such devices that escaped the rabbit, deer 

 or other animal. If it was not so well protected, the 

 large cactus. Echinocactus wislizeni, some times called 

 "barrel cactus" on account of its size and shape, would 

 soon have been exterminated, for this pulpy plant con- 

 tains possibly two hundred pounds of food and water 

 for a cow or a deer, and more than a month's food and 

 water for a rabbit. But it is armed with many rows of 

 111 Hiked and protective spines, two or three inches long, 

 and so strong that they can tear the flesh like a fish- 

 hook. With a knife a Mexican strips ofif the spines and 

 the skin, and cuts the juicy white pulp into squares that 

 he boils in a crude raw sugar called "peloncillo" and 

 makes sufficient "cactus candy" to last his family for 

 many weeks. 



The great hundred-headed cactus, called by the 

 ^lexicans "pitahaya" but in our simple botanical lan- 

 guage Cereus stramineus, with spines two inches long, 

 produces in abundance a delicious fruit flavored like 

 the strawberry. 



This is about an inch in diameter, with minute black 

 seeds. It is covered with scattered groups of small 

 spines that drop at a touch when ripe, provided you 

 are accustomed to handling tliem ; if not, they stick in 

 your fingers, and break ofT, leaving the end in the flesh. 



Another characteristic of many of these plants is 

 the long life of their seeds. Many of these are provided 

 with covers that preserve them from decay, and pre- 

 vent the water from soaking them. Some of these 

 plants will remain for months with their roots and 



leaves as dry as a bone, and when a rain comes will 

 immediately revive and flower and bear fruit. 



I have seen the "resurrection plant," Selaginella lepi- 

 dophylla, growing on face of bare rocks, apparently 

 without a particle of soil or of food material except 

 that sometimes they cling where the roots may enter 

 the crevices in the rocks. These grow in such abun- 

 dance that they may be gathered by the barrel full. 

 Other plants, starting with a small root, have through 

 time become possessed of large perennial roots adapted 

 to the storing of water and of food, so that even should 

 there be no rain, as often is the case, these plants will 

 yet grow, bloom and bear fruit. 



Among some of the more prominent of this class 

 may be mentioned the Jatropha macrorhiza, with a root 

 often weighing ten pounds. The plant is about two 

 feet high, with leaves much like those of the castor oil 

 plant, t:o which family it belongs. The Mexicans use it 

 as a medicine, by stirring their coffee with a piece of the 

 fresh stem. 



Another plant with a big root is Apodenthera undu- 

 latae. This is related to the melon, and has similar 

 vines. What a relief it is, when coursing a bare, dry 

 valley where the other plants are dry and dead, to see 

 this and Jatropha with their green leaves and beautiful 

 flowers. 



Another big rooted fellow is Maximowiozia tripar- 

 tita, also of the pumpkin family, and producing a 

 small, pulpy, red fruit about an inch in diameter. The 

 roots are dull scurfy brown in color and grow deep into 

 the hard dry soil. 



Cereus gregii is another curious and drouth resist- 

 ing plant. Ail that you see of it above ground is a dry, 

 l^rown stem that you ne\"er would suppose to be alive, 



TREE-LIKE C.'\CTUS, WELL BRANCHED 

 AND ON A FIRM TRUNK. 



SIZE OF SOME PLA.NT.S riXLM.IAR TO 

 THIS REGION. 



A N.\T1\£ Ul' TIIF. MI-;.\H. .\X ,\UI1I 

 REGIONS. 



