THE MORPHOLOGICAL STUDY OF THE FRUIT, SEED AND SEEDLING OF HYDROCHARIS DUBIA (HYDROCHARITACEAE)

摘要

The structure of the fruit, seed and seedling of Hydrocharis dubia in Hydrocharitaceae were studied with lightmicroscope. The results show that the fruit has incompletely six locules with superficial placentation. The seed has anchorliketrichomes occur on the surface and with no endosperm. The seed embryo develops on the water. The hypocotyl hairsappear earlier than the primary root which develops weakly. The adventitious roots are formed with the leaf development.The paracytic stomata are present in the upper epidermis of the young leaf and the air canals are present in the mesophyll.The petiole has a sheath-like base. The seedlings usually die and only a few could develop into mature plants and thedevelopment of the species is similar to those of the other taxa in Alismatales. The study provides the morphologicalevidence for the placement of the Hydrocharitaceae in the order Alismatales.