Hydrilla verticillata

hydrilla verticillata

1. S.SUREN 20084-PDN hydrilla verticillata

2. Classification Domain: Eukaryota Kingdom: Plantae ( plants ) Phylum: Spermatophyta ( seed   plants ) Subphylum: Angiospermae (Comprising flowering plants that produce seeds enclosed in an ovary ) Class: Monocotyledonae ( comprising seed plants that produce an embryo with a single cotyledon and parallel-veined leaves ) Order: Hydrocharitales Family: Hydrocharitaceae Genus: Hydrilla Species: Hydrilla verticillata

3. Common Name – water thyme (English) Kodi paasi ( tamil ) Indian star-vine(Sinhala) Common Alternate Name of hydrilla Florida eldoa Water thyme Poo naachu Samudra sokh

4. Plant Type Annual Aquatic Herbaceous Perennial Seed propagated Vegetatively propagated Submerged monoecious or dioecious

5. Biology of hydrilla verticillata Height : Hydrilla is variable in height depending primarily on the depth of the water Leaves: The leaves are in whorls of 4 to 8 . Individual leaves measure 0.6 to 2 cm long and 2 to 4 mm wide. The margins have 11 to 39 sharp teeth per centimeter and sometimes spines on the underside along the reddish midrib.

6. Biology of hydrilla verticillata Flowers : The axial pistillate flowers are 10 to 50 mm long and 4 to 8 mm wide. The three sepals are whitish in color with three translucent petals. They arise from the tip of the stem and float on the surface of the water . The female flower resembles an inverted bell filled with a bubble. The free-floating staminate flowers have three whitish to reddish sepals petals . Both types of flowers are produced singly surrounded by a bract or spathe .

7. Reproduction of hydrilla verticillata Sexual and Asexual production can occur Within the group of submerged rooted aquatic macrophytes Hydrilla verticillata has the greatest reproductive advantage, because it has the ability to reproduce sexually through two biotypes, namely through a dioecious system of male and female flowers in different specimens, and also through the monoecious system with male and female flowers in the same specimen. Pollination occurs on the water’s surface Pollen is released from free floating male flowers and “caught” by the free floating female flowers ( Cronk and Fennessy , 2001).

8. Subterranean Tubers • Sometimes buried several centimeters below the surface. • Can sprout new shoots even after a period of 4 years. Reproduction of hydrilla verticillata Vegetative reproduction (Asexual Reproduction) • Subterranean tubers • Axillary turions • Fragments Axillary Turions • Turions form in the leaf axils at the ends of the stems , Turions abscise and fall into the sediment . , Over winter and produce new growth in the spring. Fragmentation • Spread from lake to lake by boats , Large populations found adjacent to boat ramps. and Spreads extremely fast • Total lake coverage can change drastically in just a years time

9. Weediness of hydrilla verticillata Invasive in its native range Proved invasive outside its native range Highly adaptable to different environments Tolerates , or benefits from, cultivation, browsing pressure, mutilation, fire etc Tolerant of shade Highly mobile locally Long lived Fast growing Has high reproductive potential Has propagules that can remain viable for more than one year Reproduces asexually

10. The specimens of Elodea come from the monotypic genus Hydrilla of uncertain origin, however, it is believed that it may have originated in meso -thermal waters of the Asian continent, it exhibits pantropical distribution hence it has a wide geographical occurrence, and can be found in naturalized areas of a large number of countries in Europe, Africa, Australia, North America and South America. Hydrilla verticillata is found on all continents except Antarctica. This species is native to Asia, but it is uncertain whether it is truly native to Europe, Australia and Africa. Hydrilla was first recorded in North America from 1960 and South America from 2005 World wide Distribution

11. World wide Distribution (

12. Distribution in SriLanka Source -A Study on Competition Between Hydrilla verticillata and Mayaca fluviatilis Kapila Yakandawala Wayamba University of Sri lanka Deepthi Yakandawala University of Peradeniya                     Hydrilla verticillata ( L.f .) Royle ( Hydrocharitaceae ) is a native aquatic that has been identified as an invasive aquatic plant in the Western Province. ( Bambaradeniya , 2001 and 2008). Hydrilla verticillata  is a prevailing weed in the Mahaweli irrigation networks. A recent conducted survey showed that 60% of the water bodies are infested with  Salvinia , 45% with water hyacinth and 17% with water lettuce ( Pistia   stratiotes ). ( The problem of water weeds in Sri Lanka By Lucky Amarasinghe and Ricardo Labrada )  

13. Impact Hydrilla reproduces amazingly fast, outcompeting native aquatic plants by forming dense stands that often fill the water column down to 20 feet. The decomposition of plant material in these dense stands causes reductions in the dissolved oxygen content of water. The degradation of habitat and alterations in the trophic (food chain) structure of the ecosystem often reduces fish growth rates and numbers. Dense stands impede navigation, dramatically reduce recreational opportunities and tourism, and often block irrigation canals by dramatically slowing the flow of water. Hydrilla can also interfere with hydroelectricity, by clogging intake pipes and filters, causing millions of dollars worth of damage at individual hydroelectric facilities.

14. Uses hydrilla verticillata Medicinal uses Two biologically important and structurally novel natural products,otteliones A and B, obtained from this plant. Therapeutically hydrilla plant may be used for the following purposes: digestion and gastrointestinal function, improves bloodcirculation , helps in detoxification, Good for neurological health and cardiovascular function It increasesendurance , help in blood sugar control and strengthens immunity to protect the body from invaders and slows ageing. ( Little known uses of common aquatic plant, Hydrilla verticillata (Linn. f.) Royle D K Pal* andS B Nimse )

15. Control In Srilanka Water hyacinth, one of the worst aquatic weeds in the world, has been intentionally introduced for ornamental purpose in 1904 and it is widely distributed in Sri Lanka despite its declaration as a prohibited weed under Water Hyacinth Act in 1909 and subsequently under Plant Protection Act in 1924. (The problem of water weeds in Sri Lanka By Lucky Amarasinghe and Ricardo Labrada ). Hydrilla can be controlled by physical, chemical and biological methods, or by a combination of these methods (integrated weed management ).

16. Physical management options Removes by use of machines Physical barriers Biological ControlnMethods Use by Grass Carp Chemical methods Bispyribac sodium, is the recommended for control the weed by DOA , Srilanka

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