File:Text-book of structural and physiological botany (1877) (14776298752).jpg

Identifier: textbookofstruct00thom (find matches)
Title: Text-book of structural and physiological botany
Year: 1877 (1870s)
Authors: Thomé, Otto Wilhelm, 1840- Bennett, Alfred William, 1833-1902
Subjects: Plant physiology
Publisher: New York : J. Wiley & sons
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

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Text Appearing Before Image:
oser cortical portion consisting ofonly a few cells (Fig. 426 i). True vascular bundles arealtogether wanting ; but in most other families of Mossesthere is in the centre of the stem an axis of simple struc-ture, which does not contain true vessels, but which is oftendescribed as a vascular bundle (Fig. 426 11.), This oftenconsists oLly of a few thick- or thin-walled cells, not sharplydistinguished from the parenchyma of the stem, which servefor the conduction of the sap, and therefore perform thefunction of a vascular bundle. In some Mosses there are,however, cells with thicker walls, on which may be seen avery delicate spiral striation, and which therefore, altogethercall to mind a vascular bundle. These are sometimescentral; but sometimes, as in Polytrichtim^ give place toa central medulla. Lateral branches from these bundlessometimes pass into the leaves as veins. The leaves areoften narrow, of very thin or even membranous texture, and 302 StriictiiJal and Physiological Botany, I.
Text Appearing After Image:
Fig. 426.—I. Part of a transverse section through the stem of Sphagnum cymbi- foli2an ; E epidermal cells; R thickened and coloured cortical cells; p paren- - chyma of the stem (x 320); II. central portion of a transverse section through the stem of Climachwi dendroides; G central axis ; p brown parenchyma of the stem ( x 400). special Morphology and Classification, 303 of simple structure. They usually consist, with the exceptionof the veins, of only a single layer of parenchymatous cells; IV

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