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THE AMERICAN NATURALIST [Vol. XLVIII 



is covered with small stones and pebbles and "not a tree, shrub, 

 or herb appears to hide the bare ground. The mountains are 

 naked rock, while the harsh outline of desert ranges and the 

 distant low sand ridges give no evidence of plant life. But a 

 closer examination of plain, dune and mountains reveals the 

 presence either of living forms or of the dried remains of plants 

 of a preceding moist season, in numbers and in kinds not at first 

 suspected." All of which might well describe the desert condi- 

 tions in our own southwest. This similarity is emphasized by the 

 resemblance of many of the plants to those found in our Arizona 

 deserts. Thus the "quidad" (Aeantfn/i/;* / ragm-a » fhoides) "has 

 a very close resemblance to small specimens of 'ocotillo' (Fou- 

 quieria splendens) of the southwestern United States." And 

 this resemblance extends to the structure of the spines and the 

 return of the foliage after rains. It is interesting to note that 

 the natives burn off its numerous spines, after which the stems 

 "are eaten with avidity by camels," reminding us of the similar 

 treatment and use of some cactuses in Arizoria. Further to the 

 south the vegetation is still more sparse and xerophytic, includ- 

 ing Ephedra, littama, TlalorgUni, and anions grasses, Aristida 

 pungens. Near Ouargla, the southern point reached, there are 

 places where no vegetation is present, as on the dunes, and yet 

 on the fixed sand nearby were found Euphorbia guyoniana, 

 Retama retam and Genista Sahara*. 



Much attention was siven to the root habits of the plants 

 encountered, and in the general summary which follows the 

 account of the journey comparisons are made with the root habits 

 of Arizona plants. 



With this meager introduction we must refer the reader to the 

 volume itself, which it is quite impossible to summarize in these 

 pages. One thing impresses itself forcibly upon the reader, and 

 that is that a desert is a Jnuigrg place in which the permanent 

 vegetation maintains itself against plant-eating animals by a 

 thorny or spiny protection. Yet Dr. Cannon points out that in 

 this character of spininess the American desert plants excel those 

 of the plants of the Sahara region. 



Charles E. Bessey 



