Botanical Gazette Volume . 68

Botanical Gazette Volume . 68

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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. 1919 edition. Excerpt: ...center of cylinder; X200. Fig. 4.--L. reflexum: stele showing parallel-banded arrangement of xylem with phloem occurring in bands alternating with xylem and extending across cylinder; X200. The number of protoxylem points in the stem stele ranges from 4 to n, with about 7 as the most frequent number. Sections of the young stem tip show the condition characteristic of Lycopodium, in which at about the time of differentiation of the protoxylem points the metaxylem cells are distinguishable by their large size and lack of protoplasmic content (fig. 2). There are 3 so-called types of stele to be found in L. reflexum: the radial arrangement (fig. 3), the parallel-banded arrangement (fig. 4), Fig. 5.--L. reflexum: stele showing inner cylinder of xylcm surrounding strand of phloem, most frequent arrangement found in stele of L. reflexum; Xaoo. and an arrangement consisting of an inner cylinder of xylem surrounding a strand of phloem (fig. 5). These 3 arrangements of the xylem may be found in the same stem at different levels, and are all modifications of the radial arrangement. The parallelbanded arrangement, in which alternating strands of xylem and phloem occur in parallel bands across the cylinder, seems to be correlated to some extent with the growth of roots, since this arrangement is to be found most frequently in the region where the roots arise. The arrangement most frequently found is that consisting of an inner cylinder of xylem inclosing a strand of phloem (fig. 5). From this cylinder strands of xylem radiate to the protoxylem points. The condition is very similar to the characteristic stele described for L. Billardieri. The inner cylinder does not remain intact through any great length of stem, but is frequently broken up and gives...show more

Product details

  • Paperback | 160 pages
  • 189 x 246 x 9mm | 299g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236861698
  • 9781236861696