Students' handbook to accompany Plants and their uses . 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. rainfalls of the regions wherethese plants grow. Others, asthe mesquite of the extremesouthwest, have roots that pen-etrate into the earth to extra-ordinary depths until they reachmoist soil. Still others--for
Students' handbook to accompany Plants and their uses . 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. rainfalls of the regions wherethese plants grow. Others, asthe mesquite of the extremesouthwest, have roots that pen-etrate into the earth to extra-ordinary depths until they reachmoist soil. Still others--forexample, many South Africanplants (fig. 20), some wildmorning-glories, and the big-root1 of the Pacific coast-have fleshy roots in which muchwater is stored. 28. Water roots. Most aquaticperennials, like the cat-tails, ar-rowheads, pickerel weeds, pondlilies, and many grasses andsedges, form mainly earth the other hand, some plantsnot aquatics--for example, many willows—can develop rootsindifferently either in earth or in water. Willows growing .^, H along a brook usu-ally send greatnumbers of rootsinto the earth, andalso produce a mul-titude of fibrousroots which danglein the water. Cut-tings of Wander- FIG. 21. Duckweed, a floating aquatic planting Jew (Zebrincf), At left, top view of single plant 8 times natural size; o-praninm ( Pclarao- at riSht SrouP of three ind
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Keywords: ., bookcentury1900, bookcollection, bookdecade191, booksubjectbotany
