Abstract: The seasonal changes of the ray and phloem parenchyma cells of secondary phloem in terminal branchlets of Dalbergia odorifera T. Chen (Papilionaceae), a tropical deciduous tree, were studied by using transmission electron microscopy. The changes were mainly the cyclic alternation of accumulation and ex-haustion of the storage materials including proteins in the central vacuole, the starch grains, lipoid globules and phytoferritin in the plastids, and lipoids in the spherosomes. D. odorifera did not undergo some of the cytological changes which were found in the temperate trees studied and believed to be related with the hardi-ness. Like the stuctures found in temperate trees, in D. odorifera the highly folded plasmalemma and nu-merous small vesicles pinched of by the plasmalemma appeared in the actively reserve - accumulating cells during the leaf- fall period. It was suggested that the structures play a role in translocation of the materials between the cells, while in the temperat trees the structures were considered involving in frost resistance.

Key words: Tropical tree

摘要： 利用透射电子显微镜技术研究了热带落叶树降香黄檀( Dalbergia odorifera T. Chen)末端小枝次生韧皮部韧皮和射线薄壁组织细胞的季节变 化。这些变化主要表现为细胞内贮藏物质(其中包括中央液泡中的贮藏蛋白质，质体中的淀 粉粒、类脂球和铁蛋白，以及圆球体中的类脂等)的周期性的积累和消耗。降香黄檀在冬季 落叶期不出现在温带落叶树木中看到的与抗寒有关的若干细胞学改变。降香黄檀也象温带树 木一样，薄壁细胞在落叶期形成高度折叠的质膜，并由此形成无数的小泡。有人认为，温带 树木中的这些结构与抗寒有关，但我们认为，它们在热带树木中的作用可能是实现细胞间物 质的转运。降香黄檀与温带树木薄壁细胞季节变化的差异可以解释为它们对各自生存环境条 件的适应。

关键词: 热带树木, 韧皮部, 液泡, 贮藏蛋白质, 质体, 质膜, 降香黄 檀