. Class-book of botany : being outlines of the structure, physiology, and classification of plants ; with a flora of the United States and Canada . Botany; Botany; Botany. 52 OP THE VEINS. 250^ Inter-petiolar stipules occur in a few opposite leaved tribes, as tlie Ga- lium tribe. Here we find them as mere bristles in Diodia while in Galium they look like the leaves, forming whorls. Such whorls, if complete, will bo appar- ently 6-leaved, consisting of two true leaves and four stipules. But the adiacent stipules are often united, and the whorl becomes 102 183 104 105 103, Leaf of Con
. Class-book of botany : being outlines of the structure, physiology, and classification of plants ; with a flora of the United States and Canada . Botany; Botany; Botany. 52 OP THE VEINS. 250^ Inter-petiolar stipules occur in a few opposite leaved tribes, as tlie Ga- lium tribe. Here we find them as mere bristles in Diodia while in Galium they look like the leaves, forming whorls. Such whorls, if complete, will bo appar- ently 6-leaved, consisting of two true leaves and four stipules. But the adiacent stipules are often united, and the whorl becomes 102 183 104 105 103, Leaf of Conioselinum, tiipiniiate, with sheathing petiole. 103, Leaf of Polygonum Penn- sylvanicum, with its (o) ochrea. 104, Calm of grass, with joint (^), leaf (0 ligtile (s). 105, Leaf of pear-tree, Avith slender stipules. ** 251. The Liguli; of gi'asses is generally regarded as a double axil-"" lary stipule. The leaflets of compound leaves arc sometimes furnislied with little stipules, called stipels. 252. Stipules are often fugacious, existing as scales in the bud, and falling when the leaves expand, or soon after, as in the Magnolia and tulip-tree. OF THE VEINS. 263. Leaves, simple and compound. A leaf is simple when its blade consists of a single piece, however cut, cleft or divided ; and com- pound when it consists of several distinct blades, supported by as many branches of a compound petiole. 254. Nature of veins. The blade of the leaf consists of, (1) the frame-wovk, and (2) the tissue commonly called the parenchyma. The frame-work is made up of the branching vessels of the foot-stalk, which are woody tubes pervading the parenchyma, and conveying nourishment to every part. Collectively, these vessels are called veins, from the analogy of their functions. 255. Venation is a term denoting the manner in which the veins aa-e divided and distributed. The several organs of venation, differing from each other only in size and position, may be termed the itiidvoin, veins, vei
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