MCGEK] COMMUNALITY OP DESERT LIFE 35 



The pulp masses of the larger cacti, especially the saguaro, saguesa, 

 pitahaya, and cina, are supported by woody skeletons in the form of 

 vertical ribs coincident with the external Hutiiigs; within a few years 

 after the death and decay of these desert monsters the skeletons 

 weather out, and the vertical ribs form light and strong and approxi- 

 mately straight bars or shafts, valuable for many industrial purposes; 

 while the slender arms of okatilla are equally valuable, in the fresh 

 condition after removal of the spiny armament, and in the weathered 

 state without special preparation. 



On many of the higher plain-slopes, especially in eastern Serilaud, 

 there are pulpy stemmed shrubs and bushes, sometimes reaching the 

 dignity of trees, which present the normal aspect of exogenous i)erea- 

 nials during life, but which are so spongy throughout as to shrink into 

 shreds of bark like debris shortly after death. These are the torotes 

 of the Sonoran province — common torote (J atropha cardiophylla), torote 

 amarillo {Jatropha spathulatn), torote bianco {Bursera microphylla), 

 torote prieto (Bursera laxiflora), torotito [Jatropha canescens "!), etc. 

 These plants grow in the scattered and scraggy tufts characteristic of 

 arid districts (a typical torote tuft appears in left foreground of figure 4) ; 

 they are protected from evaporation by the usual glazed epidermis, 

 and maintained by the water absorbed during the humid seasons; but , 

 they are thornless and are protected from animal enemies by pungent 

 odors, and at least in some cases by toxic juices. Like various plants of 

 the province they are measurably communal — indeed, the torotito appears 

 to be dependent on union with an insect for reproduction, like certain 

 yuccas, and like the cina and (in some degree at least) the saguaro and 

 other cacti. 



Along the lower reaches of Rio Bacuache, and in some of the deeper 

 gorges of Sierra Seri and Sierra Kuukaak, grow a few veritable trees 

 of moderately straight trunk and grain and solid wood, such as the 

 guaiacan (Ouaiacum coulteri) auA sanjuanito (Jacquinin pnngem); both 

 of these fruit, the former in a wahoo like berry of medicinal properties, 

 and the latter in a nut, edible when not quite ripe and forming a favor- 

 ite rattle-bead when dry. On the flanks of such gorges the slender- 

 branched baraprieta [Cwsalpinia (iracilis) grows up in the shelter of 

 more vigorous shrubs, its branches yielding basketry material, while 

 its fruit is a woody bean much like that of the cat-claw. In like sta- 

 tions there are occasional clumps of yerba inala or yerba de tlecha 

 (Sehastiana biloculari.s), an exceptionally leafy bush growing in straight 

 stems suitable for arrowshafts, and alleged to be poisonous from root 

 to leaf — with inherent probability, since the plant is without the thorny 

 armature normal to the desert. Along the sand-washes, especially 

 about their lower extremities wet only iu tioods, springs a subannual 

 plant (Hymenoclea monogyra) which shrinks to stunted tussocks after 

 a year or moie of drought, but flourishes in close set fens after floods; 

 though of acrid flavor and sage-like odor, it is eaten by herbivores in 



