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Developmental and Structural Section

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

Development and function of cellulosic fibers in the leaves of Gnetum gnemon.

The leaf mesophyll of Gnetum gnemon is permeated by thick-walled unlignified fibers that form an extensive anastomosing system connected to similar fibers associated with the tissue surrounding major veins. Fiber initials originate largely from cells in the sub-hypodermal layer. The fibers become multinucleate. Fibers are initiated early and their extension is partly by symplastic and partly by intrusive growth, the latter demonstrated by their tips penetrating into the central mesophyll or to the epidermis. Wall thickening does not occur until after the leaf is fully expanded. The fibers provide the main mechanical support for the leaf. However, they also have a significant water transport mechanism that maintains a highly hydrated leaf mesophyll, facilitating gas exchange. These leaf fibers are contrasted with the stem tension fibers that are a distinctive feature of extra-xylary tissues in Gnetum gnemon. Apart from their different origins, leaf and stem fibers differ in cell wall ultrastructure.


1 - Harvard University, Harvard Forest, Petersham, Massachusetts, 01366, USA
2 - Fairchild Tropical Botanic Garden, 11935 Old Cutler Rd., Coral Gables, Florida, 33156, USA
3 - National Tropical Botanical Garden, The Kampong, Coconut Grove, Florida, 33133, USA

Keywords:
fibers
tension wood
Gnetum
leaf veins
leaf anatomy.

Presentation Type: Paper
Session: 52-11
Location: Alpine A (Snowbird Center)
Date: Wednesday, August 4th, 2004
Time: 4:00 PM
Abstract ID:102


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