Abstract Detail

Developmental and Structural Section

Tomlinson, P. Barry [2], Fisher, Jack B. [1].

Adventitious roots and shoots are strongly polarized in seedlings of Rhizophora mangle.

The viviparous seedling of Rhizophora mangle is an elongated hypocotyl detached from the parent tree as its propagule, eventually to be stranded in a horizontal position in the intertidal zone. Subsequent anchorage and establishment in a vertical position presents major problems that are largely overcome by the robustness and longevity of the seedling. These include: 1) Longitudinal symmetry which is strongly polarized between shoot (plumular) and root (radicular) ends. Traumatized seedlings maintain polarity by developing either adventitious roots or shoots and easily survive even when as much as 10 cm is cut off from either end. 2) Transverse polarity is shown in the radicular end as a gravimorphic response that erects seedlings by eccentric development of tension wood fibers. This greatly promotes early establishment. 3) Seedlings retain vital processes after many months because they store abundant starch and are protected against desiccation. Hypocotyl robustness and self-erection are the keys to the development of mangal.

1 - Fairchild Tropical Botanic Garden, 11935 Old Cutler Rd., Coral Gables, Florida, 33156, USA
2 - National Tropical Botanical Garden, The Kampong, Coconut Grove, Florida, 33133, USA

Keywords:
adventitious shoots
tension fibers
reaction wood
mangrove
seedling anatomy
gravitropism.

Presentation Type: Poster
Session: 32-19
Location: Special Event Center (Cliff Lodge)
Date: Tuesday, August 3rd, 2004
Time: 12:30 PM
Abstract ID:103