in Sri Lanka - Ministry of Environment

petioles (e.g. Nymphaea), or with long stems rising through the water, bearing leaves withrelatively short petioles (e.g. Nymphoides).(3) Submerged plants: Plants that are generally rooted at the bottom, and the vegetative partsentirely submerged. At the time of flowering, the flowers and some leaves may emergefrom the water. These plants could be thallus-like, attached to rocks (members of thefamily Podostemaceae), with long stems rising through the water bearing leaves, androoting at the nodes (e.g. Hydrilla), or with short stems bearing leaves in a basal rosette,and often producing stolons (e.g. Blyxa). These plants are restricted to depths wheresufficient light reaches them through the water for photosynthesis.(4) Emergent plants: Often with rhizomes, rooted in mud, with shoots emerging above thewater (grasses and sedges). These plants occur in relatively shallow water or towards theperiphery of a water-body.Sri Lanka harbors over 370 aquatic or wetland plant species of which 12% are endemic tothe country. The aquatic flora include 135 Eudicots, 205 Monocots, 4 members belonging tosuper-orders Nymphaeanae and Ceratophyllanae, and 28 ferns and fern allies. The island’saquatic flora is taxonomically placed under 64 families of which 28 are Eudicot families, 24 areMonocot families while 14 are ferns and fern allied families. The families with entirely aquaticmembers include Alismataceae, Aponogetonaceae, Cabombaceae, Ceratophyllaceae,Hydrocharitaceae, Menyanthaceae, Najadaceae, Nymphaeaceae, Nelumbonaceae,Podostemaceae, and Potamogetonaceae. The largest aquatic plant family, the Cyperaceae(Sedges), has 69 species followed by the Scrophulariaceae and Poaceae (Grasses).Hydrocharitaceae, Eriocaulaceae, Lentibulariaceae, Commelinaceae and Asteraceae also havea considerable number of aquatic members. All these aquatic species are native to the country,except for few species such as Eichhornia crassipes (Mart.) Solms-Laub., Limnocharis flava (L.)Buchenau and Salvinia molesta D. Mitch., that are recent introductions and have spread rapidlyand become naturalized in many parts of the country. Forty one (41%) percent of the island’saquatic flora are now threatened and listed under different categories during the present RedListing. This needs to be considered seriously during the preparation and implementing of thewetland conservation and management plan. Three percent (3%) of aquatics are consideredunder the Probably Extinct category (CR(PE)) while 5.6% are considered under the CriticallyEndangered (CR). Most plants under both these categories are distributed in the lowland wetzone in and along small and large streams, and rivers, swamps, marshes and paddy fields,especially in the Kalutara, Colombo, Ratnapura and Kegalle districts. The rocky rapids of theMahaweli river in the Gannoruwa-Hallolluwa area in Kandy are another site that harbors manyof these plants. The Endangered category (EN) accounts for 12% of aquatic flora while theVulnerable and the Near Threatened categories (NT) account for 10% and 10.6% respectively.The family Araceae harbors the highest number of endemics which include 10 species ofthe genus Cryptocoryne and 7 Lagenandra species. Cryptocoryne is a very vulnerablegenus where all of its members have been recognized as threatened in the past and presentevaluations for Red Listing. The Cryptocoryne mainly occurs in the south-western lowlandever-green rain forests, central midlands, central western lowlands in the semi-deciduousmonsoon forests having a seasonal change in precipitation and few are scattered in thedry zone riverine forests. These species mostly thrive in slow running water or seasonallyinundated soils. They occur both submerged or emerged depending on the growth stage,vegetative or reproductive. Five Cryptocoryne are placed under the Critically Endangered188