Biodiversity & Endangered Species

摘要: Hydrophyte is a life form of plants. Podostemaceae are unique aquatic lithophytes growing exclusively in sunny rapids and waterfalls with seasonal water-level change the tropical subtropical climates. However habitat is, it apparently uniform across distributional range. Vegetative plants grow submerged tightly adhering on water-worn rock surfaces violent currents during rainy season. The become flowering fruiting dry season when water level lowers, finally exposed dry. small simple flowers many species anemophilous, while colorful scented others entomophilous. seeds usually dispersed by wind, wet, adhere to mucilaginous seed coats then juveniles submerged. only other similar fluvial environments Afro-Madagascan Hydrostachyaceae. pantropical most diversified America. About 20 genera ~137 all three subfamilies occur America, ~17 ~80 two subfamilies, Africa Madagascar, ~18 ~84 same Asia Australia [1]. pattern unique. Many restricted single rivers or river systems, local areas various sizes. Migration probably not very successful, partly because suitable dotted widely isolated, establishment success from exalbuminous little stored nutrition low. morphological diversity characterized recurrent large-gap differences. earliest occurred at origin common ancestor Hypericaceae. Hypericaceae have body plan typical terrestrial angiosperms aerial primary shoot underground root, together forming vertical axis. In basal subfamily Tristichoideae (Podostemaceae), like angiosperms, forms between cotyledons, root end hypocotyl, though reduced. Additionally an adventitious develops lateral side Hypericum. derived but species-rich Podostemoideae rudimentary no devoid root. formed hypocotyl constitutes prostrate axis substituting for reduced This alteration major that allowed invade severe environment. Abrupt changes even sister genera. one genus, plant comprises large shoots flank creeping hypocotyl. rootless, consisting crustose developed axil cotyledon. It likely involved loss/gain remarkable modification shoot. Loss associated gigantic per plant, happened another lineage differences reflected high frequency monotypic (22 [41%] 54 genera). Those large-gapped plans evolved leading anchoring organ Podostemaceae. dorsiventral surface varies ranging subcylindrical ribbon-like, crustose. bears (in shoot-less species) tufts leaves scattered dorsal surface. green functions as photosynthetic organ, well. Indeterminate growth characteristic supported Shoot Apical Meristem (SAM), embryonic tissue, present apex stem/shoot. There SAMs whereas they absent Podostemoideae, largest subfamily, irrespective being long lacking. SAM-less species, apparent elongates intercalary leaves. Plant morphology governed genetic which primarily operate tissue called meristem patterns gene expression stem leaf, specific angiosperms. Podostemaceae: ordinary comparable e.g., model plants, Regulatory genes play crucial roles maintenance (SAM) Tristichoideae, extraordinarily leaf formation [2]. Consequently, interpreted be fuzzy complex comprising Podostemoideae. this causes morphology. Conservation imminent problem worldwide. Of Neotropical up third (15-37%) 16% more single-river two-river endemics [3]. Two thirds data deficient, respectively. impact threat construction dams hydroelectricity leads loss habitat, consequently diversity.