Botanique et Bioinformatique de l'Architecture des Plantes, UMR 5120 CNRS, TA40/PS2, Boulevard de la Lironde, F-34398 Montpellier cedex 5, France;
Am J Bot. 2005 Sep;92(9):1444-56. doi: 10.3732/ajb.92.9.1444.
Mechanical properties are investigated in Desmoncus orthacanthos and D. polyacanthos from French Guiana, South America. Differences in size and axis stiffness are related to different trellis requirements and habitats. The leaf sheath surrounds the stem, increasing stiffness of young self-supporting stages and apical parts of older climbing plants. Senescence of the leaf sheath reduces stiffness of older climbing axes of both species. Its eventual loss in D. orthacanthos facilitates deformation into coils and loops when plants slip from their supports following senescence of leaves bearing attachment organs. In smaller climbing axes of D. polyacanthos, the senescent leaf sheath remains attached and axes rarely form loops and coils below attachment. An increase in stiff mechanical properties toward the base of both species is radically different from that of many dicotyledonous lianas. Besides the presence of attachment organs, stem mechanical properties of Desmoncus are similar to those of erect though not fully self-supporting stems of Bactris major, a sympatric species of the sister group genus to Desmoncus. The climbing habit in Desmoncus may have evolved via (1) heterochronic processes including early elongation of internodes relative to increase in stem diameter (reduction of the establishment phase) and (2) increased persistence of leaf sheaths.
来自南美洲法属圭亚那的 Desmoncus orthacanthos 和 D. polyacanthos 的力学特性得到了研究。大小和轴刚度的差异与不同的格子要求和栖息地有关。叶鞘环绕茎，增加了年轻的自支撑阶段和较老的攀援植物的顶端部分的刚度。叶鞘的衰老降低了两种植物较老的攀援轴的刚度。在 D. orthacanthos 中，当承载附着器官的叶子衰老时，植物从支撑物上滑落，其最终丧失会使茎容易变形为线圈和环。在 D. polyacanthos 较小的攀援轴中，衰老的叶鞘仍然附着，轴很少在附着下方形成环和线圈。两种植物基部的刚性机械性能的增加与许多双子叶藤本植物的截然不同。除了存在附着器官外，Desmoncus 的茎机械性能与同属的直立但不完全自支撑的 Bactris major 的茎机械性能相似，Bactris major 是 Desmoncus 的姐妹群属的同域物种。Desmoncus 的攀援习性可能是通过（1）异时过程进化而来的，包括节间相对于茎直径的早期伸长（建立阶段的减少）和（2）叶鞘的持续时间增加。
