Biomechanics and development of rattans: what is special about Plectocomia himalayana Griff. (Calamoideae, Plectocomiinae)?
2006
ISNARD, SANDRINE
Mechanical and morphological studies of Plectocomia himalayana (subtribe Plectocomiinae) revealed characteristics that differ strongly from species of subtribe Calaminae (Calamus and Daemonorops). In species of Calaminae tested previously, the contribution of the leaf sheath drastically increases stiffness in juvenile axes and towards the apex of older plants. In P. himalayana the relative contribution of the leaf sheath to axis stiffness is less and leaf sheath senescence does not strongly reduce axial stiffness as observed in Calamus and Daemonorops. Natural aerial branching, only described in Korthalsia and Laccosperma among rattans, is common in P. himalayana. Aerial branching and adventitious roots occur frequently along old stems allowing autonomy of stems, following mechanical injury and promoting vegetative propagation. The climbing habit is known to have evolved at least twice within the Calamoideae. The results observed here suggest that climbing habits may differ in detail and that different 'climbing strategies' may have evolved within the subfamily Calamoideae resulting from: (1) variable stem flexibility, (2) the variable mechanical role of the leaf sheath (Calamus-Daemonorops) and (3) production of branches and aerial roots conferring a higher degree of architectural plasticity (Plectocomia).
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