286 SHREVE: ACROSS THE SONORAN DESERT 
palms give the traveler the impression of being in some Moroccan 
village, far from the confines of the United States. 
Throughout northern Sonora the vegetation of the flood- 
plains and alluvial areas is more nearly like that of southern 
Arizona than is the vegetation of the hills and the outwash slopes 
or ‘“‘mesas.” The “Little Peaklet’’ from which the town of 
Pitiquito derives its name is the first place that the cardon, 
Pachycereus Pringlei, is detected. This is an arborescent form 
similar to Carnegiea but more massive and unlike it both in its 
Characteristic vegetation between Pitiquito and the Picu 
FIG. 1. 
Mountains, Sonora. The trees are Parkinsonia, Olneya, and Prosopis. The 
cactus is Lophocereus Schottit. 
coarser armature and in the more acute angle of insertion of its 
branches. Pachycereus grows here together with Carnegiea and 
Lemaireocereus, and the abundant Opuntia Bigelovii, making a 
landscape that would arrest the attention of any traveler. 
After crossing the broad bed of the Magdalena River the 
remainder of the journey to the Gulf is across small valleys with 
unimportant streamways and small ranges of volcanic hills. 
Between Pitiquito and the Sierra Picu, the last range of hills 
crossed, the course lies between 1100 and 2000 ft. in elevation. 
On the coarse, gravelly mesas the characteristic plants are 
chiefly species of wide distribution in the Sonoran Desert, such 
as Covillea tridentata, Parkinsonia microphylla, Olneya tesota, 
