The elements of botany : structural and physiological : with a sketch of the artificial modes of classification, and a glossary of technical terms / by John Lindley.

  • John Lindley
Date:
1861
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Credit: The elements of botany : structural and physiological : with a sketch of the artificial modes of classification, and a glossary of technical terms / by John Lindley. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

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    that of the veins of the leaves. When they belong to the leaflets of com- pound leaves, they are called stipels. Stipules usuMlly appear later than leaves in the order of devtlopraent. But in Baptisiathe case is Reversed. 284. Sometimes only one stipule is formed, tlio other being constantly abortive, as in Azara. 285. Stipules are sometimes transformed into leaves : they sometimes have buds in their axils ; and may be therefore considered rudimentary leaves. 286. Whatever arises from the oase of a petiole, or of a leaf if sessile, occupying the same place, and attached to each side, is considered a stipule. The appearance of this organ is so extremely variable, some being large and leaflike, others being mere rudiments or scales, others spines, ten- drils, &c., that botanists are obliged to define it by its position, and not by its organization. 287. Stipules must not be confounded with cellular appendages of the edge of the petiole, as in Dogbanes. 288. Stipules, the margins of which cohere in such a way that they form a membranous tube sheathing the stem, are called ochrece ; Ex. Rhubarb. . The conclusions, as to stipules and leaves, to which De Mrrckliii's investigations have led liim, are the following : — a. Leaves rH grow upon an axi«, and their first form is thud of a tubercle. The lobes, divisions, or leHflets found in tlie lower halt'of a completely formed leaf, appear at a later period than those of the uppi-r half. h. The origin;.] tubercle answers lo the point ot a leaf or to the point of a common pefio'e. c. All kaves, at a particular period of their growth, are simple. d. In all leaves the blade and ihe upper end ot the | etiole are formed earlier thini ihe stipules and the lower half of ihe petiole. (Tina is not true of Baptitiia.) e. There are two lorinations in the compound leaf; it is at first f-imple ; it then becomes pinnated. It is scarcely probable ihiit pinnated leaves owe their origin, like ihe first, to the axis of the lenflet. f. Whether a leaf be simple or compound, the petiole must be considered as an immediate extension ol the axis ; it certainly exercises considerable influence on the formation of the baf. g. 'J'he stipel appears later than the part of the leaflet at whose base it appears ; its growth is generally much slower than that of the stiiiule.