in Sri Lanka - Ministry of Environment

populations of species such as Cryptocoryne, Aponogeton and Lagenandra. Even thoughrules and regulations exist, many exporters have their own undisclosed suppliers and areas forcollection which include the Kelani Valley basin and small streams in areas such as Mawanelle,Avissawella, Bulathkohupitiya, Ruwanwella and Yatiyantota in the Lowland and central wet zoneof Sri Lanka (Seneviratne, 2002) and dry zone rivers including Malwathu oya and Kuda oya.Alien invasions: Many ornamental aquatic Invasive Alien Species (IAS) have beenencountered in the country’s water bodies in the past, where ‘Japan Jabara’ or Water hyacinth(E. crassipes) is one of the best examples which has become a menace to aquatic ecosystems.Salvinia molesta, a free floating water fern, has also established its name in theinvasive alien species list being only second to E. crassipes. Pistia stratiotes, even though ithas not set records, is another alien invasive species that has got established in local waterbodies drawing considerable attention. These plants still continue to cause a threat to thenative aquatics in many wetlands including Bellanwila-Attidiya marshes, Anaiwilundawa, andKalametiya & Lunama Kalpuwa wetlands, and many reservoirs. Several dry zone lakes havebeen infested with E. crassipes during the restoration of tanks for agriculture in the recentyears. Further, the floods in 2011 in the dry zone have facilitated the spread of E. crassipes intonew destinations, infesting new water bodies.Apart from these invasives, several other plants could be identified as naturalized aquatics inlocal water bodies, notably Vallisnaria spirallis L., Egeria densa Planch. and Cabomba carolinianaA.Gray. Yakandawala and Yakandawala (2007) reported three other additions Ludwigia sedioides(Humb. & Bonpl.) H.Hara, Mayaca fluviatilis Aubl. and Echinodorus spp., found in the local waterbodies in the Western Province of Sri Lanka. All three plants are popular aquatics in aquariumsand landscaping. The most recent addition to the list is of great interest as it opened up anew chapter in invasive alien plant research in Sri Lanka while highlighting the importance ofPlant Systematics and proper identification of organisms. The flawed identification of a violetflowered water-lily as Nymphaea nouchali Burm.f. and subsequently narrating as the nationalflower of Sri Lanka (‘Nil manel’), have overlooked its threat to the local biota and invasiveness.This exotic violet flowered water lily has been silently invading the local water bodies where itwent unnoticed due to the erroneous identification and its popularity as an ornamental plant.Studies have further revealed hybrid populations between the native N. nouchali and the alienviolet flowered Nymphaea with intermediate characters (Yakandawala and Yakandawala, 2011).Global researches have attributed the origin of invasiveness to hybridization, especially between anative and invasive alien species and where the native is at a risk of extinction (Yakandawala andYakandawala, 2011 and references therein). The detection of hybrid populations of Nymphaeahas opened up avenues to initiate studies locally on this novel area of hybridization betweennatives and invasive alien species.Even though Sri Lanka harbors a larger number of naturally occurring aquatics, there is a highdemand for certain exotic aquatic plants in the export market. This has resulted in the privatesector importation of exotic plants into the country for propagation and exportation. Accordingto recent studies 386 plant species are traded as ornamental aquatic plants in the country(Yakandawala, et al., unpublished). The plants belongs to 46 plant families that included39 angiosperm families with 64 genera, 6 fern/fern allies with 6 genera and 1 liverwort. Ofthe recorded ornamental aquatic plants, 76% were non-natives or exotics. The list includedtwo plants that are currently listed on the IAS list in Sri Lanka of which one is on the global192