. The elements of botany for beginners and for schools. Botany. 50 LEAVES. [SKCTION 7. The wholo surfaco, is covered l)y n transparent skin, tlip Epider/nis, not niililce tliat. wliicii covers t he surface ol' all IVosh shoots. 12 k Note that the leat'-blade expands iiorizontally, — that is, normally presents its laces one to the sky, the other to the ground, or when the leaf is erect the upper face looks toward the stem that bears it, the lower face away from it. Whenever this is not the case there is something to be explained. 125. The framework consists of zcood, — a fibrous and tough mater
. The elements of botany for beginners and for schools. Botany. 50 LEAVES. [SKCTION 7. The wholo surfaco, is covered l)y n transparent skin, tlip Epider/nis, not niililce tliat. wliicii covers t he surface ol' all IVosh shoots. 12 k Note that the leat'-blade expands iiorizontally, — that is, normally presents its laces one to the sky, the other to the ground, or when the leaf is erect the upper face looks toward the stem that bears it, the lower face away from it. Whenever this is not the case there is something to be explained. 125. The framework consists of zcood, — a fibrous and tough material which runs from the stem through the leaf-stalk, when there is one, in the form of parallel threads or bundles of fibres; and in the blade these spread out in a hori- zontal direction, to form the ribs and cei>is of the leaf. The stout main branches of the framework are called the Ribs. When there is only one, as in Fig. 112, 114, or a middle one decidedly larger than the rest, it is called the Midrib. The smaller divi- sions are termed Feins; and their still smaller subdivisions, Veinlets. The latter subdivide again and again, until they be- come so fine that they are invisible to the naked eye. The fibres of which they are cpmposed are hollow; forming tubes by which the sap is brought into the leaves and carried to every part. 126. Venation is the name of the mode of veining, that is, of the way in M-hich the veins are distributed in the blade. This is of two principal kinds ; namely, the parallel-veitied, and the netied-veined. 127. In Netted-veined (also called Reticulated') leaves, the veins branch off from the main rib or ribs, divide into finer and finer veinlets, and the branches unite with each other to form meshes of network. That is, they anastomose, as anatomists say of the veins and arteries of the body. The Quince-leaf, in Fig. 112, shows this kind of veining in a leaf with a single rib. The Maple, Basswood, Plane or Buttonwood (Fig. 74) show it in leav
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbotany, bookyear1887
