College Botany; Structure, Physiology and Economics of Plants

College Botany; Structure, Physiology and Economics of Plants

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1920 edition. Excerpt: ... more or less soluble substances, more especially the mineral constituents. There is also a gradual downward movement of the soluble organic constituents through the protoplasmic contents of the sieve tubes and from them, by diffusion, into the actively growing cells. In the lower land plants, such as the liverworts and mosses, the tissues are simple and the water travels for short distances and its movements can be explained by osmosis. But in the larger plants, in which the distances for transport are great, the tissues-are correspondingly complex and highly differentiated and the transport much more difficult to explain. Girdling.--Trees will live, after being girdled, for the remainder of the season, because the flow of water and dissolved food materials is unaffected by the girdled part, but will die during the winter, because the girdling prevents the downward flow of the protein materials which are normally stored in the roots for use the following spring. The girdling of a branch of a fruit tree or vine will-prevent the downward flow of protein through the phloem and cause it to be diverted to the fruit, which becomes larger than normal. These fruits are said to be forced. The same result is frequently brought about by winter injury of trees at the surface of the ground; some of the cortex and phloem are killed, which results in a partial or complete girdling. Other L0sses.--But transpiration, guttation, bleeding, etc., do not explain all the losses by the growing plant. Gases are given off by the foliage and other green parts (see page 196). Carbon dioxide and other compounds are given off by the roots. Leaves and flowers, twigs, fruit and branches fall and the bark peels off slowly and is renewed from within (see page 52). The...show more

Product details

  • Paperback | 88 pages
  • 189 x 246 x 5mm | 172g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236886003
  • 9781236886002