. Plants and their uses; an introduction to botany . cular. The ultimate branchesof the framework of a leaf are often nothing but single vessels. Be-sides the woody and the vascular , which serve mainly forconducting fluids, ferns and higher plants often develop .strands orlayers of liardencd, tliick-walled cells whose function is mainly togive strength or afford protection. Su(!h tissue is termed scleren-chyma • in general, or sclerotic or prosenchyma inparticular. An outer layer of the cortex as at (FL) often becomessclerotic and thus contributes much arlditional .strengt
. Plants and their uses; an introduction to botany . cular. The ultimate branchesof the framework of a leaf are often nothing but single vessels. Be-sides the woody and the vascular , which serve mainly forconducting fluids, ferns and higher plants often develop .strands orlayers of liardencd, tliick-walled cells whose function is mainly togive strength or afford protection. Su(!h tissue is termed scleren-chyma • in general, or sclerotic or prosenchyma inparticular. An outer layer of the cortex as at (FL) often becomessclerotic and thus contributes much arlditional .strength to a co-lumnar organ. The jiarencliyma of a fern-stem serves very largelyfor the storage of reserve food in the form of starch. From theepidermis of various parts may arise hair-like or scale-like out-growths which serve mainly to protect organs that are very youngor especially need to be covered. Whereas in multicellular plants Fibro-vascu-lar < , a fiber; vascuhan, a small vessel. Scler-enchj-ma < Gr. skleros, hard. THE FERNS 539. Fig. 366.—Fern Stems {Aspidium spp.). A, underground stem (rhizome)of A. Filix-maH with rind removed to show the net-work of fibrovascularbundles. B, one mesh of this net-work enlarged to show the brancheswhich enter a leaf to form its framework. C, cross-section of a rhizome(.4. corioceum) slightly enlarged to show the cylindrical fibrovascularsystem formed of two main-strands, the upper (o) smaller than thelower (n), and the finer branches of these which enter the leaves. D, thefibrovascular cylinder of the same, removed and laid out flat aftersplitting the low^er strand {u, u) in halves, leaving the upper strand (o)in the middle unbroken, as also the finer strands {h, h, b, b) which enterleaves and roots, and the larger strands (j:, x, x, x, x) which enterbranches of the stem. (Sachs, Mettenius.) of simpler structure it was sufficient to distinguish merely differenttissues, in the higher plants the differentiation has progresse
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1913
