The natural history of plants, their forms, growth, reproduction, and distribution; . , consisting ofseveral leaflets, collapse like houses built of cards when touched, and under the treeslate in the autumn lies a confused heap of leaflets and leaf-stalks, the latter some-times looking Kke long rods (as, for example, in the Ailanthus and Gymnocladus),sometimes almost like long bones (as in the Horse-chestnut, fig. 93). Frequently the layer of separation is so situated on the leaf-stalk that after the FALL OF THE LEAF. 361 detachment a small portion of the stalk remains on the branch. This is t
The natural history of plants, their forms, growth, reproduction, and distribution; . , consisting ofseveral leaflets, collapse like houses built of cards when touched, and under the treeslate in the autumn lies a confused heap of leaflets and leaf-stalks, the latter some-times looking Kke long rods (as, for example, in the Ailanthus and Gymnocladus),sometimes almost like long bones (as in the Horse-chestnut, fig. 93). Frequently the layer of separation is so situated on the leaf-stalk that after the FALL OF THE LEAF. 361 detachment a small portion of the stalk remains on the branch. This is the case inthe so-called Syringa, or Mock Orange {Philadelphiis), where the scale-lik^ partwhich is left has to protect the bud situated just above the leaf-stalk. In some trees and shrubs defoliation is very rapid, in others only gradual. Inthe Japanese Maidenhair Tree {Ginkgo hiloha), the formation of the separation-layerand the detachment of the leaves is completed in a few days; in hornbeams andoaks the stripping of the foliage continues for weeks, and frequently only a portion. Fig. 93.—Leaf-fall of the Ilorse-chestnut (Jiscuiiis Uippoccuianuin). of the dead leaves is thrown off in the autumn, the remainder not until the close ofthe winter. It is also worthy of remark that in some trees the leaf-fall begins at the end ofthe branches and gradually proceeds towards the base, while in others the contraryis the case. In ashes, beeches, hazels, and hornbeams, the apices of the branches areleafless when the lower parts still bear firmly-fixed foliage; in limes, willows,poplars, and pear-trees, on the other hand, the lower portions of the branches areseen to lose their leaves early in the autumn, the denudation gradually extendingupwards; on the extreme ends of the branches some leaves, as a rule, obstinatelyremain for a long time, until they also are at length whirled away by the firstsnowstorm. 362 THE VASCULAR TISSUES AND TRANSPIRATION. CONNECTION BETWEEN THE STRUCTURE OF THE
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectbotany, bookyear1902
