Are There Foliar Gaps in the Lycopsida?

Edward C. Jeffrey
Botanical Gazette
Vol. 46, No. 4 (Oct., 1908), pp. 241-258
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Are There Foliar Gaps in the Lycopsida?


1. True foliar gaps occur immediately above their corresponding leaf-traces and are not lateral to the leaf-traces. 2. Foliar gaps are absent in Phylloglossum, although a superficial examination of the anatomy of this genus might lead to the conclusion that the perforations in the tubular stele, which are sometimes lateral to the outgoing leaf-traces, are to be regarded as true foliar lacunae. 3. Foliar gaps are likewise absent in Tmesipteris, and recent statements as to their presence are based on misinterpretation or misconception. Perforations in the stele are here also found sometimes lateral to one or more leaf-traces, but these cannot be regarded as true foliar gaps. 4. Foliar gaps are absent in the Lepidodendreae and the Sigillariae, but in the more modern species of the latter perforations of the tubular central cylinder are sometimes found, which have the same relations and are susceptible of the same explanation as are the similar perforations in Phylloglossum and Tmesipteris. 5. Foliar gaps are unquestionably absent in the cone axis of Equisetum, and on the basis of comparative anatomy are absent also in the vegetative stem. Similar statements apply to the reproductive and vegetative axes of Calamites. Archeocalamites has no foliar gaps in its vegetative stem. 6. The Lycopsida as defined by the author are clearly marked off from other plants by a palingenetically microphyllous habit, the absence of foliar gaps in the tubular stele, and by the possession of sporophylls with adaxial sporangia. They constitute a great natural phylum.

Notes and References

This item contains 14 references.

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    Phil. Trans. Roy. Soc. London B.195:119-I46. 1902.
  • 3
    KIDSTON, R. Internal structure of Sigillria elegans. Trans. Roy. Soc. Edinburgh41:533-550. 1905.
  • 4
    Phylloglossum. Archives Bot. du Nord de la France1885:112. fig. 102.
  • 5
    Morphology of the sporangium-bearing organs in the Lycopodiaceae. New Phytologist 7:41-60. i908.
  • 7
    Recherches sur les Tmesipteridees. Archiv. Bot. du Nord de la France30:-. 1882.
  • 8
    Anatomy and morphology of Tmesipteris. Annals of Botany22:63-89. 1908.
  • 9
    The origin of a land flora. London. 1908.
  • 10
    New Phytologist 7: 126. 1908.
  • 11
    Structure, development, and affinities of Equisetum. Boston Soc. Nat. Hist. Memoirs 5: no. 5. p. 176.
  • 12
    Affinities of the genus Equisetum. Amer. Nat. 39:273-285. 1905.
  • 13
    Origin of a land flora, chaps. 14 and 42.
  • 14
    Steinhohlen-Calimarien. Atlas zu den Abhandlungen Gelog. Specialkarte V. Preussen 2': Berlin. 1871.
  • 15
    Anatomy of Palaeostachya vera. Annals of Botany21:375. 1908.
  • 16
    New Phytologist 7: 125. 1908.