Introduction to structural and systematic botany, and vegetable physiology, : being a 5th and revedof the Botanical text-book, illustrated with over thirteen hundred woodcuts . selves in the cortical integument, or rind. As the stem increases, newbundles, springing from the bases ofmore recently developed leaves, are atfirst directed towards the centre of thestem, along which they descend forsome distance, growing more slenderin their course, and then, curving out-wards, mostly terminate hi the is partly in consequence of the co-hesion of these obliquely descendingfibres to the false b
Introduction to structural and systematic botany, and vegetable physiology, : being a 5th and revedof the Botanical text-book, illustrated with over thirteen hundred woodcuts . selves in the cortical integument, or rind. As the stem increases, newbundles, springing from the bases ofmore recently developed leaves, are atfirst directed towards the centre of thestem, along which they descend forsome distance, growing more slenderin their course, and then, curving out-wards, mostly terminate hi the is partly in consequence of the co-hesion of these obliquely descendingfibres to the false bark, that the lattercannot, as in Exogens, be separatedfrom the wood beneath. The manner in which the woody threads are consequently interwoven is shownin Fig. 185. The Palm-like Yuccas of the Southern States offerbeautiful illustrations of the kind. 205. Endogenous stems, instead of having the oldest and hardestwood at the centre and the newest and softest at the circumference,as in ordinary trees, are softest towards the centre and most compactat the circumference. They increase in diameter with the increas-ing number of woody bundles (which multiply as new leaves are. FIG. 185. Vertical ami transverse section of a young endogenous stem, showing the curv-ing of the fibres. 116 THE STEM. produced), as long as the rind is capable of distention. In someinstances, as in the arborescent Yuccas and the Dracaenas or Dragon-trees, the rind remains soft and capable of unlimited growth; but inthe Palms, and in most woody Endogens, it soon indurates, and thestem consequently increases no further in diameter. The wood ofthe lower part of such stem is more compact than the upper, beingmore filled with woody bundles, and the rind is firmer, from thegreater number of ligneous fibres which terminate in it, and fromits proper induration. 206. Palms generally grow from the terminal bud alone, andperish if this bud be destroyed; they grow slowly, and bear theirfoliage in a cluster at the summit
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Keywords: ., bookauthorgra, bookcentury1800, bookdecade1860, booksubjectbotany
