Students' handbook to accompany Plants and their uses . re left un watered fortwo or three days, they begin towilt. Field crops and sometimeseven shade trees do the same intimes of severe drought. Manyplants, when grown in dry ground,will flower and seed in a dwarfedcondition. The common groundsel,a weed not infrequently found inlong-tilled fields and about door-yards (lig. 19), under favorableconditions grows to be a foot 01more in height, but in the very drysand along Mediterranean beachesthis plant flowers and seeds whenonly an inch high. 27. Roots of desert plants. Theplants of desert and
Students' handbook to accompany Plants and their uses . re left un watered fortwo or three days, they begin towilt. Field crops and sometimeseven shade trees do the same intimes of severe drought. Manyplants, when grown in dry ground,will flower and seed in a dwarfedcondition. The common groundsel,a weed not infrequently found inlong-tilled fields and about door-yards (lig. 19), under favorableconditions grows to be a foot 01more in height, but in the very drysand along Mediterranean beachesthis plant flowers and seeds whenonly an inch high. 27. Roots of desert plants. Theplants of desert and other dryregions frequently show strikingpeculiarities of form and structure,and among these is an unusualdevelopment of the root able to live under extremelydry conditions are known as xero- phijtes. Familiar examples of these are century plants and xerophytes, as the cacti, have a rather widely spreadingroot system extending quite near the surface of the earth ; sucha root system makes the most of every one of the infrequent. FIG. 19. Effect of deficientwater supply on growth Tin- plant is ijroiindsel, a commonEuropean weed \vliicli uro\Ys tfrom lli to 18 indies hivji. At l>is shown the relative height ..fthe saiiu- plant \\hen t;n>\vn invery dry sands along Mediter-ranean beaches. Modified alter Flora Daiiica ROOTS AND THEIR RELATION TO PLANTS 29
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Keywords: ., bookcentury1900, bookcollection, bookdecade191, booksubjectbotany
