The Phenotypic Plasticity Of Water And The Forecast Of Evolution Of The Invasive Plant Hydrocotyle Vulgaris

Hydrocotyle vulgaris is origin the south of North America, it have highly ornamental value because ofits green, litter, and lovely leaves. It has massively spread in many coastal areas of wetlands since beintroduced into China as a kind of waterscape plant, and now, it has attracted attention as an invasive alienspecies. To understand the biomass distribution of moisture phenotypic plasticity of H. vulgaris, we potted itand control water of5moisture gradients: aquatic, wet, middle, xeric and drought; To understand theanatomical structures of H. vulgaris by comparative anatomy of aquatic, wet and middling moisturegradients H. vulgaris’s leaf, stem, runners, and anatomical structure comparison of3kinds of Umbelliferaeto forecast the trend of the evolution of H. vulgaris organizational structure may produce. The resultsshowed:1. H. vulgaris underground runners’ node has a strong ability to germination, it most suitable habitat iswet habitats, their average number of leaves are101per pot after90days for living. Their aerial andunderground biomass, length of stems and size of leaves are changed with the trend of increase first and thendecrease related to the reduction of water content of matrix, but it shoot ratio changed with the trend ofdecrease first and then increase; water content of plant is positively correlated with habitat moisture. Thebiomass allocation of H. vulgaris shows it has high moisture phenotypic plasticity.2. With the reduction of the moisture content of the habitat, leaf stomata of H. vulgaris reduced, butstomata index increased. The thickness of the up and lower epidermis cells and palisade tissue increased, thethickness of spongy tissue and blade reduced; stem diameter and stomata length decreased, vasculardiameter and the number of catheter increased; runner diameter, medullar diameter and the thickness of theparenchyma increased and then decreased content with the reduction of the moisture, stomata lengthdecreases, but the number of vascular bundles and conduit gradually increased. Leaves, stems and runnersanatomical structural of H. vulgaris changed showed it got adaptability to drought.3. Hydrocotyle sibthorpioide var. batrachium have thicker up and under epidermal cells of leaves thanHydrocotyle sibthorpioide increased by96.14%and89.35%, and it leaf thickness, the ratio of palisade tissueand spongy tissue, stem diameter, runners’ parenchyma and diameter, the number of catheters were increasedsignificantly. These difference of organizational structure showed that H. sibthorpioide var. batrachiumadapt to cold and drought better than H. sibthorpioide. The unique organizational structure underground ofxeric H. vulgaris’ node of runners shows it resist code and drought well, it vegetative organs may changesimilar accord to H. sibthorpioide–H. sibthorpioide var. batrachium evolution trend.4. The aquatic extract of leaves and roots of H. vulgaris get allelopathy on seed germination andseedling growth of3kinds of plant which are sensitive of allelopathy substance: radish (Raphanus sativus),Chinese cabbage (Cucumis sativus), and cucumber (Brassica chinensis). Its leaves extract get strongerinhibitory effect to the3plants’ seed germination than roots extracts, and it get stronger inhibitory effect tothe3plants’ roots than leaves.