We see in grasslands a plant response to rainfall and other climatic conditions which, with a little more rainfall, or in locally wet places, always produces woody growth, either as tongues of woods in river bottoms or the parklike landscape, already mentioned. If, however, the rainfall is too low to produce even the grasses and their associated herbs, an entirely different type of vegetation usurps these still more dry regions, resulting in some of those strange plants of the deserts, among which water storage is practically universal, as is the ability to live for long periods without rainfall. DESERTS Of absolute deserts there are none in North America, for no part of it is so dry that plants of some sort do not grow, and in fact in hardly any part of the world are there regions of any considerable extent where plant life of any kind is lacking. There is a small section of northern Chile and adjacent regions on the western slopes of the Andes where nothing grows, and the traveler is met with a cheerless landscape of bare ground and sandy or stony soil. There is no record of it ever having rained in such places, and if there be only a single rain consisting of a fraction of an inch a year, a few plants, usually scraggly low herbs with thick leaves or else quick-flowering annuals will be found. But there are hundreds of thousands of square miles of the earth’s surface where the rainfall is sufficient to produce plant life, but where it hardly exceeds five or at most six inches in a year, and in some regions is less than two inches. From several different stations in the desert area of our own Southwest the average annual rainfall is about five and a half inches. Such regions produce a desert type of vegetation and are popularly, if not properly, called deserts. The largest is of course the Sahara in Africa, but there are huge tracts in Arabia, China, Thibet, Australia, South Africa, and in some other countries where the conditions for plant life are so unfavorable that only in the better sites are plants found at all. In all deserts there are very large areas entirely without plants, due to shifting sand or other local conditions, which, added to the generally unfavorable climate, make plant life impossible. With rainfall so low and in most of the regions the temperature so high, the vegetation must be insured against too rapid transpiration. Perhaps the best illustration of how high transpiration both in plants and in man may be in such regions is gained by a statement of D. T. MacDougal, who writes of man traveling in the desert that “the amount (of water) thrown off the skin is correspondingly great, and if the loss is not made good, thirst ensues and ten hours’ lack of water may thicken the tongue so that speech is impossible.”