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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Licence: Public Domain Mark

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.

    47/280 (page 31)
    Such is the usual explanation of the cause of the zoned appearance of the woody system of Exogens ; but I have seen stems of trees from Calcutta, which I was assured had produced four rings a year, and the common Garden Beet, which produces in its roots many rings, is an example of zoned gro^vth, which cannot be explained by the common theory. 177. The secretions of plants are deposited most abundantly in the oldest concentric layers ; while those layers which are most recently formed contain but a slio-ht deposit. 178. When the tissue of the concentric layers is filled with secretions, it ceases to perform any vital functions. 179. The dead and fully formed central layers are called the heart-ivood. 180. The living and incompletely formed external layers are called the alhumum. 181. Upon the outside of the wood lies the Bark, which, like the wood, consists of concentric layers. 182, It may be distinguished into four parts : 1. Epidermis^^ ; 2. the Epiphlceum^^ * , 3. the Alesophloeum^^ ^'^ ; and 4. the Endophloeum or Liher^^ But these are blended into one fibro-cellular mass in many cases. ] 83. Each of these parts increases by successive additions to its own inside, except the epidermis, which is never renewed. 184. The Epiphloeum and Mesophlceum are both formed of cellular tissue only ; but their cells arc placed in different directions with respect to each other. The former is often large .and soft, and may separate spontaneously from the young layers forming beneath it: as in Cork, which is the epi- phloeum of Quercus Suber, the cork-barked oak. J 85. The Endophlccum, or Liber, consists of cellular tissue resting on the alburnum, of laticiferous tissue (49), and of pleurenchyma (32). The tubes of the latter are often thickened rapidly by a deposit of sedimentary matter ; in which case, sections of the tubes present the appearance of concentric circles. Hence arises the toughness of the tubes of pleurenchyma which occur in the liber, and are manufactured into cordage, as in the Lace-bark tree, the Lime-tree, <kc. 86 is the same as Fipr. 8 ), three full yeai-s old, with the layers of hark move thick and numerous, and the limits of each year's growth of wood indicated by figures on the upper edge. Fig. 87.—Section of an Oak br.mcli eight years old.