The Development And Morphological Study Of Menyanthes Trifoliata And Nymphoides Peltatum (Menyanthaceae) And Their Taxonomy Significance

This paper use the plants Menyanthes trifoliataL. and Nymphoides peltatum (Gmel.) O.Kuntze (Menyanthaceae) as the materials which be a more detailed studied from the morphology of the vegetative and reproductive organs , embryo development (zygote to seed embryo), seed germination and seedling development. The study reveals both their structure adapt to aquatic habitat and compare to previous work which study in Gentianaceae .As two kinds of aquatic plants, they all have rhizome which couble be go across , leaf margins are beneficial to aquatic life with drainage.The petals have the multicellular trichome on both sides.The pollen surface have three colporate and strip decoration. The seed coat epidermal cells of Menyanthes trifoliate exist the cavity and the seed margin have the single-cell hair of Nymphoides peltatum which benefical for spread in the wate.The roots deeply into the soil, especially the petiole specialize a erect,sheath-like structure of the stem and the succulence level of leaves will be reduced ,the stoma arised from the lower surface of young leaves when Nymphoides peltatum be forced to choose aerial life when the absence of water in the field.The plants (except seeds) of Menyanthes trifoliata and Nymphoides peltatum all have the well-developed aerenchyma.Menyanthes trifoliata and Nymphoides peltatum have the embryonic stem which be uniserial with few cells,and it will be degradate or disappear in the phase of the heart-shaped embryo.The root tip could be well developed in the phase of the seed embryo.The end of the hypocotyl will be enlargement in the phase of seeding development in Menyanthes trifoliata.And the Nymphoides peltatum hold a different way of Menyanthes trifoliata in the seeding development: the root hairs arise from the mature area as soon as the root tip out the seed coat when seed germination,do not form the callet and hypocatylehair.This article provide a detailed basis of the developmental morphology in which the Menyanthes trifoliata and Nymphoides peltatum isolated from Gentianaceae and forms as a separate family. And with the structures that the root have no secondary structure ,the stems which smooth without wings ,the leaves alternate, corolla arranged in a valvate form and the bud is not distorted, with the trichome in the base of the inner surface of the petals and cellular type of the endosperm which are not found in the Gentianaceae. Although they have the structure which adapt to the aquatic habitats, this is their long-term adaptation of the water environment for which can completely live in the terrestrial conditions. But their seedling development characteristics are different from primitive aquatic group(Nymphaea tetragona).Our research that hold a extensive study for the aquatic plants, especially the significance of the difference between the seedlings development for the evolution of the system will provides a new way of thinking.