. Agriculture [microform]. Agriculture; Agriculture. lO AGRICULTURE. The stalk is compact and strong, built for holding up a heavy weight. When young the stalk and branches are green in color; as they grow older the color becomes darker and duller, and the soft, smooth skin changes to hard, rough bark. The stalk and branches are much stiffer than the roots ; if they were as pliable as the roots they would not be able to hold themselves up in the form that we see. Most plants, however, are pliable enough to yield to strong wind and thus avoid being broken. The last thing to be noticed here in r
. Agriculture [microform]. Agriculture; Agriculture. lO AGRICULTURE. The stalk is compact and strong, built for holding up a heavy weight. When young the stalk and branches are green in color; as they grow older the color becomes darker and duller, and the soft, smooth skin changes to hard, rough bark. The stalk and branches are much stiffer than the roots ; if they were as pliable as the roots they would not be able to hold themselves up in the form that we see. Most plants, however, are pliable enough to yield to strong wind and thus avoid being broken. The last thing to be noticed here in regard to them is that what is called " the grain " goes along and not across the branch and stalk. We can split a piece of wood along its grain, but we have to saw or break it if we wish to divide it across the grain. What would be the effect of a strong wind upon plants, trees, forests, if the grain ran across instead of along the stalks, limbs, trunks, and branches ? The most noticeable points in connection with leaves are their shape, their number, and their color. The leaf is generally flat and very thin. Its outline or form varies with different kinds of plants. Contrast the thick, needlii-shaj)ed leaf of the pine and the thin, long, pointed blade of grasi; with the leaves of the oak, maple, basswood, and willow. Take a green maple leaf: draw its outline ; trace the frame- work upon which it is formed. Then glue or paste it between two sheets of paper or cloth and dry carefully. Pull these two sheets apart and thereby split the leaf. We thus see that the leaf is a thin web stretched upon a framework of fine branches, and we observe that the branching of these Fig. 12.âSection of a Leaf. /I, row of cells ., r ^\ i c â ⢠i-rr forming skin on upper side ; B, row of ribs of the leaf VarieS HI dlffcr- cells next to skin ; D, next row of cells; . i ⢠i r i r ..i C, air spaces in leaf; E, inner portion of Cnt kuids of leaVCS ; further, CI. filled with sap; /<
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Keywords: ., bookauth, bookcentury1800, bookdecade1890, booksubjectagriculture
