File:Text-book of structural and physiological botany (1877) (14590020278).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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nto an outer cortex consisting of thick-walled cells, and a thin-walled parenchymatous inner cortex(Fig. 438 r and r^), the latter passing over gradually intothe fundamental tissue. The activity of the cambium ofthe vascular bundles is limited, as also is their diametralgrowth, the vascular bundles growing chiefly at the apex.The bundles of the entire plant are in direct communicationwith one another above and below, and thus form a systemof fibro-vascular bundles. They divide and ramify in thestem, forming a complete network, and send out branchesinto the leaves. In the roots, on the contrary, the bundlescoalesce into a single central or axial vascular bundle. Theseparate bundles, as seen in transverse section, are some-times roundish and sometimes ribbon-shaped, and are special Moiphology and Classification, 309 usually separated from the cortical and medullary cellsby a vascular bimdle-sheathy consisting of prosenchymatouscells thickened on one or on all sides, and generally fibri-
Text Appearing After Image:
Fig. 436.—Black s^^Xe&rmort, Asplenitim Adimttum-nigrmn, showing a part of therhizome (natural size, with a single pinna magnified). 31 o Structural and Physiological Botany. form and strongly lignified. The oldest parts of the bundlescontain narrow vascular cells with annular or spiral thicken-ings ; the portions formed later having, on the other hand,scalariform cells. ^ True vessels occur but rarely. In the

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