Phylogenetic and evolutionary studies of rheophytes in the everwet tropics

1.在博梅奥采集或记录到的蕨类植物有60种，远多于货车Steenis（1981）记录的12种，接近博梅奥记录的被子植物82种。这表明婆罗洲蕨类植物的多样性比目前所了解的要大得多。流生芽苞植物的特征是：叶多层次;茎坚韧，通常匍匐;植株高度低;茎分枝合轴，植株呈席地状。在这些特征上，流生芽体（配子体）与维管流生植物的孢子体相似，而不像配子体.对热带流生植物和相关旱地植物叶片解剖学的比较研究表明，流生植物叶片狭窄的部分原因是其叶肉细胞较旱地植物的宽叶细胞膨胀少，臂短，细胞间隙小.一种流生植物和相关旱地种的叶发育研究，以检验流生狭叶在个体发育过程中是如何形成的。在 ...更多信息 早期流生狭叶原基比旱地阔叶原基小。在细胞扩展阶段，狭叶比旱地叶更早停止扩展，这可能是由于异时性（幼态）。狭叶的细胞间隙越小，光合速率就越低，这可能是因为狭叶的光合作用越强，而陆生植物的光合作用越强，因此狭叶的光合作用就越差.分子系统学研究表明，流生薇菜与陆生薇菜的亲缘关系较近。japonica（亚洲东部）的分布比陆生O. regalls（北美，欧洲等），尽管后两者在形态上彼此相似。结果证实了该植物为旱生植物.本文报道了流生和陆生薇菜配子体发育的研究。japonica的配子体形态差异不显著，但流生配子体比旱地配子体生长快，产生孢子体早; lancea采取世代适应策略。少

1. About 60 species of fern rheophytes collected or recorded from Bomeo are much more than 12 species van Steenis recorded in 1981 and approach 82 angiosperm species recorded from there. It indicates much greater diversity of the fern rheophytes of Borneo than understood at present.2. Rheophytic bryophytes can be characterized as : leaves multi-layered ; stems tough, often creeping ; plants low in height ; stem-branching sympodial and plants matted. In these characters, rheophytic bryophytes (gametophytes) resemble the sporophytes of vascular rheophytes rather than the gametophytes.3. Comparative leaf anatomical study of tropical rheophytes and related dry-land species shows that rheophytic stenophylly is due partly to less expanded, short-armed mesophyll cells and consequent smaller-spaced intercellular spaces than broad leaves of dryland species.4. Leaf developmental study of a rheophyte and related dry-land species to examine how rheophytic stenophylls are formed during ontogeny. At … More an early stage the primordia of the rheophytic stenophylls are smaller than those of dry-land broad leaves. During the cell-expansion stage the stenophylls cease to expand earlier than the dry-land leaves, presumably due to heterochrony(paedomorphosis). Smaller intercellular spaces of the stenophyll result lower photosynthetic rate, which is assumed to make the rheophytes difficult to grow in terrestrial habitat in which photosynthetically more active dry-land species grow.5. Molecular systematic study shows that the rheophytic Osmunda lancea is more closely related to the terrestrial O. japonica (eastern Asia) than to the terrestrial O. regalls (North America, Europe etc.), although the last two morphologically resemble one another. The result confirms that the rheophyte is derived from the dry-land species.6. Developmental study of gametophytes of the rheophytic Osmunda lancea and the terrestrial O. japonica shows that there is no marked difference in gametophyte morphology but the rheophytic gametophytes grow faster to produce more sporophytes earlier than the dry-land ones, and that O. lancea takes generation-specific adaptive strategy. Less