This is a somewhat complex province, geographically speaking. 

 As a belt, it would under theoretical conditions run across the 

 lower half of the latitudes it now occupies — that is to say 

 between the twenty-eight and thirty-first parallels — but, because 

 of the major ocean and atmospheric currents, it is today pushed 

 north to the thirty-sixth parallel, about the region of the 

 Mojave and Death Valley. At the same time, it extends south 

 farther than it should (due to a set of lesser factors) and includes 

 the whole central section of the peninsula of Baja California. 

 In fact, it here runs almost due north to south. 



Its boundaries are ill defined. To the north it merges with the 

 "gray deserts" (as defined by the soils) of the Great Basin. To the 



west it disappears under the coastal mountain ranges of 

 Southern California but appears again on the coast from 

 Los Angeles south to Baja California. To the east it likewise 

 disappears under the Arizonan or southern block of the 

 Southern Montane Province, but it shows itself again on the 

 Colorado Plateau. To the south of this upland massif, it peters 

 out about Phoenix, Arizona, and from there to the Gulf of 

 California on the Sonoran coast it merges with the Southern 

 Scrub Belt. Southward, it hops the Gulf and cuts right through 

 the peninsula of Baja California. 



Its isolation from the central or Chihuahuan Desert Province 

 is occasioned by the northward swing of the Southern Scrub 

 Belt and by the fact that the subtropical grasslands (savannahs) 

 and the orchardbush likewise approach the north Mexican 

 border, while there are many mountain ranges that connect the 

 Arizonan block to the Sierra Madre Occidental athwart this 

 neck. Many of these mountains rise high enough for montane 

 conifers and even other forest growths to maintain a footing on 

 their peaks. There is, in fact, a broken bridge of uplands 

 connecting the two, which, combined with the scrublands, 

 completely separates the western or Sonoran from the central 

 or Chihuahuan Desert Province. 



The Sonoran Province is composed of lowlands through which 

 flows only one substantial river — the remnants of the 

 Colorado — though the Gila is not altogether insignificant. Upon 

 its surface, however, there lie a great many mountains, both 

 isolated and in chains, and the backbone of Baja California is 

 sharp and in many places precipitous. To the northwest, there 

 are some true deserts such as the Mojave, culminating in the 

 sunken, sub-sea-level Death Valley. The province as a whole is a 

 sort of vegetational sink, the inner recesses of which are drier 

 and less vegetated than the periphery, which merges with 

 the scrublands on all sides. Here may be seen as typical desert 

 conditions as anywhere on this continent. 



In the Barrels, the buds arise from special protuberances, called 

 areoles, just above the ordinary areoles that produce the spines. 

 (Areoles are unique structures in the plant world, being special 

 areas of tissue from which joints and spines are developed and 

 from which flowers may arise, while roots will sprout from them 

 on bits of cactus that fall to the ground.) In the Hedgehogs, the 

 flowers erupt from the skin of the plant just above the older 

 spine-bearing areoles. In the Pincushions, the flowers grow be- 

 tween the skin tubercles or from their upper sides and have no 

 connection with the spine-bearing areoles. The Cerei are the 

 most difficult to define; they range in size from the three biggest 

 cactuses, the Giant or Pringle's, the Organpipe, and the Saguaro, 

 to tiny vinelike things no thicker than a pencil. Among these 

 last are the famous night-blooming cactuses. All these produce 

 their flowers at or just below the tips of their limbs. 



As mentioned earlier, cactuses are encased in impermeable 

 coats of special leathery tissue usually plentifully supplied with 

 wax, and they sometimes have a waxy external covering besides. 

 Everything about them is devised to store water, so that, even 

 without a fresh supply of it, they maintain themselves for long 

 periods, in some cases for years. There are places where they 

 live that have on occasion remained without a drop of rain for 

 as much as four years. However, too much water can kill them, 

 and they must have rest periods when they do not absorb any 

 through their roots. It may therefore be thought curious that 



many of them live in saturated jungles. Cactuses therein are, 

 however, epiphytes — that is to say, they grow on other plants 

 (but are not parasitic on them) — and they straggle about on the 

 branches. In these forests they would "drown" in the saturated 

 air were it not for their impermeable skins. Then again, in many 

 of these areas of very high rainfall there is often a prolonged 

 comparatively rainless period or one when the rain comes down 

 in sudden great spurts of short duration. As soon as it stops, the 

 tree limbs dry off completely. 



DESERT DEVILS 



The Chollas, which tend to develop into treelike forms, are con- 

 structed like branching strings of green sausages with little 



Facing page, above: The White-tailed Deer, shown here 

 alerted by the flash of the photographer's strobe light, is as 

 much at home in the desert as in lush forests, and is quite 

 common in the Sonoran region. 



Below: The little Spotted Skunk or Spilogale has silky fur 

 and hunts small nocturnal desert animals. Like all other 

 members of the skunk family, it has what are euphemisti- 

 cally called "scent glands." 



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