Anomalous secondary vascular tissue inHelminthostachys zeylanica (Ophioglossaceae) |
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Authors: | Akira Takahashi Masahiro Kato |
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Affiliation: | (1) Department of Biology, College of Bio-Medical Technology, Osaka University, Osaka, Japan;(2) Present address: Natural History Museum and Institute, Hyogo Prefectural Board of Education, 5-10-1 Shimoyamate-dori, Chuo-ku, 650 Kobe, Japan;(3) Botanical Gardens, Faculty of Science, University of Tokyo, 3-7-1 Hakusan, 112 Tokyo, Japan |
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Abstract: | The vascular anatomy ofHelminthostachys zeylanica was examined with special reference to anomalous secondary tissue. Primary xylem development gradually takes place centrifugally. In branched rhizomes with destroyed apices, the vascular cylinder apical to the insertion of branch traces is generally composed of primary xylem, accessory xylem, inner parenchyma of radially arranged cells, outer parenchyma of irregularly arranged cells, and partly crushed phloem, listed in order going outwards. The accessory xylem as well as the inner parenchyma ofHelminthostachys zeylanica is probably secondarily produced, partly to contribute to the branch traces, in a position corresponding to that of secondary vascular tissue developed from a normal cambium inBotrychium sensu lato. It is suggested that although a cambium is lacking inHelminthostachys zeylanica, the secondary vascular tissues are comparable between the genera. The phylogenetic implication of this tissue is discussed. |
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Keywords: | Progymnospermopsida Ophioglossaceae Helminthostachys zeylanica Anomalous secondary vascular tissue phylogeny anatomy |
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