Abstract:

Jiangsu Province which is one of the provinces having many lakes, is situated in latitude 30˚40′—35˚07′ north, longitude 116˚22′—121˚55′ east. It extends across southern temperate, northern subtropic and central subtropic bioclimatic belts. There are rich aquatic plants. The distribution of aquatic plants in lake is closely relative to the physical and chemical environments,particularly to the depth and transparency of lake water.Aquatic plants in this province have 62 species, 48 genera and 30 families, having four main life forms which are related to the position of plants on the water level:(1) Emergent plants with vegetative parts normally emerging above the surface of the water;(2) Attached plants with floating leaves;(3) Free-floating plants; (4 )Submerged plants generally attached to the bottom by roots.The adaptation of various life forms to different depths of water often results in a marked zonation of aquatic vegetation from shore to deep water. In a typical situation, the shallow water near the edge would be occupied by a zone of emergent plants. As the water becomes deeper these are replaced by rooted forms with floating leaves which in turn are fringed by a submerged plants zone and or free floating species.The floristic composition, formation and succession of aquatic vegetation are analysed and described.There are four basic vegetation types with sixteen main communities in aquatic vegetation in Jiangsu Province. Their major communities are grouped into following types:

1. Emergent types:Phragmites australis community, Zizania latifolia community; Nelumbo nucifera community; Typha angustifolia community.

2. Floating-leaved types:Euryale ferox community; Trapa incisa var. quadricaudata community; Nymphoides peltatum, Hydrocharis dubia community; Potamogeton distinctus community.

3. Floating types:Leman minor, Spirodela polyrhiza community;Azolla imbricata, Salvinia natans community; Hydrocharis dubia community.

4. Submerged types : Myriophyllum spicatum, Hydrilla verticillata, Ceratophyllum demersum community; Myriophyllum spicatum community; Potamogeton malainus community; Potamogeton crispus, Vallisneria gigantea, Najas minor community.

The distributions of all communities mentioned above have been individually described.

The economical uses of aquatic vegetation are intensively discussed. It is a plant resources using as fish food, feed for livestock, sources of fibre for paper-making and weaving mats, agricultural tools and green manures. They can be used as food, green vegetable, medicine, the construction material of dwellings and fences, as well as for the purification of water bodies.