DESERT REGIONS OF NORTH AMERICA. ds | 
Two trees pass under the name torote blanco; one is a Terebinthus with 
papery buff-colored exfoliating bark; the other is a tree of very similar 
appearance, but leafless in the winter season and suggestive of Jatropha 
(plate 11). 
It was among these desert hills west of Torres that an opportunity 
was offered to see a Papago Indian extract from a bisnaga (Echinocactus 
emoryt), or barrel cactus, water with which to quench his thirst. He cut 
the top from a plant about 5 feet high and with ablunt stake of palo verde 
pounded to a pulp the upper 6 or 8 inches of white flesh in the standing 
trunk. From this, handful by handful, he squeezed the water into the 
bowl he had made in the top of the trunk, throwing the discarded pulp 
on the ground. By this process he secured 2 or 3 quarts of clear liquid, 
slightly salty and slightly bitter to the taste, but of far better quality 
than some of the water a desert traveler is occasionally compelled to use. 
The Papago, dipping this water up in his hands, drank it with evident 
pleasure, and said that his people were accustomed not only to secure 
their drinking water in this way in times of extreme drought, but that 
they used it also to mix their meal preparatory to cooking it into bread. 
GUAYMAS. 
The flora in the harbor of Guaymas is of a xerophytic character simi- 
lar to that at Torres, but apparently subjected to severer conditions of 
aridity. The creosote-bush (Covillea tridentata), the plant most widely 
distributed in the more severely dry deserts of the southwestern United 
States, appears here again after a long intermission across the plains of 
northern and middle Sonora. Many of the trees and shrubs are of the 
same species as those found in the vicinity of Torres, but are of smaller 
growth. 
The hecho (Cereus pecten-aboriginum), whose bur-like fruits are used 
for hair-brushes by the Indians, had appeared along the railroad near the 
station of Escalante south of Torres, but at Guaymas it was replaced by 
a species of similar habit, with different fruit, Cereus pringler. A remark- 
able mixture of plants occurred along the beach in the salt waters of the 
harbor where small mangroves (Avicennia and Rhizophora), which we are 
accustomed to associate with the humid tropics, grew side by side with 
Cereus thurbert, C. pringler, and other characteristic desert plants (plates 
12 and 13). 
TEHUACAN. 
In 1906 a visit was made to southern Mexico for the purpose of mak- 
ing some observations upon the species with storage organs which were 
known to be abundant in that region, and also to get living material of 
these plants and of the cacti for experimentation. 
