. Plants and their uses; an introduction to botany . he two leaf branches, which in the fertile orsporangial segment miglit result in each sporangium being borneon a little stalk or branclilet of its own. We may well imagine thatwonderful possibilities of development lay before such a .type asthis as soon as it itself on the edges of swamps or on landwhere food and moisture abounded. It could then afford to delaythe i)roduction of spores until it had built a thick, tall stem, bymeans of leaves made larger and larger year after year and devotedentirely to making food so that a surp
. Plants and their uses; an introduction to botany . he two leaf branches, which in the fertile orsporangial segment miglit result in each sporangium being borneon a little stalk or branclilet of its own. We may well imagine thatwonderful possibilities of development lay before such a .type asthis as soon as it itself on the edges of swamps or on landwhere food and moisture abounded. It could then afford to delaythe i)roduction of spores until it had built a thick, tall stem, bymeans of leaves made larger and larger year after year and devotedentirely to making food so that a surplus might be stored in the , a very large number of sporangia might l)e produced uponmuch-branched spore-sac-leaves; and these, held high in the air,could scatter their spores most effectively. THE FERNS 535 We know that during the coal age many tree-ferns like thePecopteris shown in Fig. 277 (page 299), apparently near ofkin to the adder-tongues, produced stout trunks bearing acrown of ample leaves nearly twenty meters above Flu. 361).—Tree-Ferns and Herbaceous Ferns. (Baillon.) At the present day tree-ferns such as the one shown inFig. 360 abound in moist, warm regions, although the fernsmost common in northern lands are more like the smallerones shown in the same illustration. Thus it would appearthat a certain amount of degeneration has attended theadaptation of ferns to the more stringent conditions of cold 536 LIFE-HISTORIES
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1913
