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AMERICAN HOMES AND GARDENS 



October, 1906 





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A Belated Turtle Plodding His Weary Way 



Where the Meadow-lark Secretes Her Nest 



acquaintance of innumerable little neighbors you knew not of 

 before; your world is enlarged, your pleasures multiplied, and 

 you come to feel that you have found a veritable garden of 

 Eden in the weed-field. And this is done easily, readily and 

 without real exertion. There is vigor given to a day's outing 



when there is some definite end attached to it, something real 

 to do, and something interesting to find. The camera yields 

 no greater joy than when put to nature-study. Lasting me- 

 mentoes of one's walks, its work is never toilsome and its 

 pleasures always delightful. 



Desert -plants as a Source of Drinking-water 



STRANGER left alone in a desert would 

 die of thirst, and yet there is water in all 

 deserts, and both the native animals and the 

 native races know how to find it. This water 

 is gathered and stored by plants, which have 

 built and filled their reservoirs for their own 

 purposes, but which yield it up, when required, for the use 

 of the animal world. 



The extent of the root system in desert-plants, by means 

 of which they absorb their water from the soil, is often as- 

 tonishingly great. In the Mohave Desert of California a 

 branching cactus (Opuntia echinocarpa) , 19 inches in 

 height, was found to have a network of roots extending over 

 an area of ground about eighteen feet in diameter. The 

 roots lay near the surface, at a depth of two to four inches, 

 a situation which enabled them to take advantage of a single 

 substantial downpour and, before the precipitation had been 

 again absorbed into the parched air, to suck up a supply of 

 water sufficient, if need be, for a whole year's use. Other 

 desert plants send their roots deep into the ground for water, 

 and a certain shrubby species of acacia found about Tucson. 

 Arizona, possesses, according to Professor R. H. Forbes, a 

 double-root system, in which one series of roots spreads out 

 horizontally, close beneath the surface, and a second series, 

 sharply defined, goes directly downward into the soil. Such 

 an arrangement enables the plant to seize upon water either 

 from light precipitation or when deeply percolating under 

 dry-stream beds. 



While the devices for absorption in desert-plants are un- 

 usual, the mechanical contrivances by means of which these 

 plants are enabled to retain the moisture they have absorbed 

 are still more remarkable. Other factors being equal, the 

 amount of water evaporated from a plant is proportional to 

 the area of its green surface, which, in ordinary plants, is a 

 foliage surface. A specimen of coffee-plant (Coffee arabica), 



weighing 20.5 grammes, is found to have a leaf surface com- 

 puted at 164,476 square millimeters, which gives a ratio of 1 

 to 8,023. A specimen of bisnaga or barrel-cactus (Echino- 

 cactus emoryi), in the conservatories of the Department of 

 Agriculture at Washington, weighing 77,000 grammes (170 

 pounds) and without leaves, has a green stem surface of 

 1,032,320 square millimeters, with a ratio of 1 to 13.4. Thus 

 for each gramme of tissue a coffee-plant, representing the 

 ordinary vegetation of a humid climate, has a green surface 

 599 times greater than that representing a gramme of tissue 

 in cactus; or, in physiological terms, the coffee-plant, other 

 factors being equal, is provided with means for the transpira- 

 tion of 600 times as much water as the cactus. 



The practical value of such plants as a source of drinking- 

 water is, of course, very great. Life upon many of the 

 American deserts would be wholly insupportable without 

 them, and travel quite impossible. They show, in a very 

 striking way, some of the economical devices whereby Nature 

 undertakes to remedy the evils she herself creates. To the 

 casual observer the part they take in correcting Nature's 

 drawbacks — and the deserts surely rank high in such a list — 

 is unquestionably their greatest interest; but the scientific 

 problems of water-collection and water-preservation which 

 they present have a special interest of the deepest import. 



To the scientist it is this practical aspect which is of para- 

 mount importance. Here is a group of plants whose eco- 

 nomic value in other ways has not been ascertained perform- 

 ing natural functions of a most surprising kind and under 

 most difficult conditions. Nor is the amazement they must 

 create in the human mind limited to the mere preservation 

 of water. They are Nature's reservoirs, not for man alone, 

 but for animals, who have, for their part, discovered their 

 life-preserving qualities, and make as ready use of them as 

 men do themselves. 



