The Scientific Research of Barry Tomlinson
Stevenson, Dennis Wm. .
Architecture of non-seed vascular plants.
Branching systems of seed free vascular plants are not as diverse as those of seed plants. The extinct and extant lycopods have branching patterns based upon dichotomous branching. Similarly, this is seen, also, in the Psilotaceae although the interpretation for Tmesipteris is controversial. The leptosporangiate ferns exhibit varying patterns of branching as the result of detached meristems (potentially residual meristematic areas in internodal regions). Generally, the position of detached meristems although variable amongst the leptosporangiate ferns is constant for individual species. They may occur in internodal regions, on the acroscopic margins of petioles, on the basioscopic margins of petioles, or associated with stipules as in the Marattiaceae. In many ferns, adventitious buds occur on leaf tips such as in Asplenium rhizophyllum or in pinnae axils as in Diplazium proliferum. The point is that non-seed vascular plants lack precise relationship of leaves and buds as in the axillary bud of seed plants. There are exceptions where there appear to be axillary buds in some leaf axils in Botrychium and Helminostachys in the eusporangiate ferns and in the Hymenophyllaceae in the leptosporangiate ferns. It is this general constrain of axillary buds that appears to have led to greater variability in plant architecture in the seed plants as opposed to that of non-seed plants. This variability of architecture in seed plants has led to such forms as monopodial growth, sympodial growth, epiphyllous inflorescences, etc. Ferns. in particular, appear to have developed a vast range of leaf architectures.
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1 - New York Botanical Garden, Bronx, NY, 10458, USA
Presentation Type: Symposium or Colloquium Presentation
Location: 552A/Convention Center
Date: Wednesday, August 4th, 2010
Time: 1:45 PM