Developmental and Structural Section
Fisher, Jack B. .
Seedlings in a fire prone community bury their buds by axis contraction after germination.
To document repositioning of seedling buds, selected perennials (20 dicotyledons and one cycad) native to the fire-prone pine rocklands of South Florida were germinated and measured for 4-5 mo. Height of the cotyledonary node above the soil decreased because of axis contraction or bending in eight species. Anatomy suggested that two mechanisms operate: (1) production of G-fibers (= tension wood fibers) in six species (all Fabaceae); and (2) collapse of parenchyma cells in two species (Convolvulaceae and Zamiaceae). Contraction or bending of the hypocotyl and/or taproot moved the cotyledonary and later buds of the seedling closer to the soil surface or buried them. Other species have little or no hypocotyl elongation, thus keeping the cotyledonary node at soil level. These mechanisms may protect the lateral buds and/or the shoot apex from injury by fire or other environmental stresses and allow resprouting.
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1 - Fairchild Tropical Botanic Garden, 11935 Old Cutler Rd., Coral Gables, Miami, Florida, 33156-4299
seedling growth and development
Presentation Type: Oral Paper:Papers for Sections
Date: Monday, July 28th, 2008
Time: 10:15 AM