Nymphoides peltata

Nymphoides peltata (S. G. Gmel.) Kuntze, Revis. gen. pl. 2:429. 1891 (Syn: Limnanthemum nymphoides (L.) Hoffmanns. & Link; Limnanthemum peltatum S. G. Gmel.; Limnanthes nymphoides (L.) Stokes; Limnanthes peltata (S. G. Gmel.) S.F.Gray; Menyanthes natans Lam.; Menyanthes nymphoides L.; Nymphoides europaea Fisch. ex Steud.; Nymphoides flava Druce; Nymphoides nymphoides (L.) Britton; Nymphoides orbiculata Gilib.; Nymphoides peltatum (S. G. Gmel.) Britten & Rendle; Schweyckerta nymphoides (L.) C. C. Gmel.; Villarsia nymphoidea (L.) St. Lager; Villarsia nymphoides (L.) Vent.; Villarsia peltata (S. G. Gmel.) Roem. & Schult.; Waldschmidia nymphoides (L.) Wigg.);          
Austria, Belgium, England, Czech Republic, Slovakia, Germany, Netherlands,
Hungary, Poland, Romania, Denmark (introduced), Switzerland (introduced), Sweden
(introduced), Portugal, Spain, France, Sardinia, Italy, former Yugoslavia,
Albania, Bulgaria, Greece, Latvia, Lithuania, C-, N- & E-European Russia,
Belarus, Ukraine, Northern Caucasus, Georgia [Caucasus], Armenia, Azerbaijan,
Siberia (W-Siberia, C-Siberia), Russian Far East, Kazakhstan, Uzbekistan, Japan
(Honshu, Shikoku, Kyushu), Taiwan (introduced), South Korea, Mongolia, China
(Anhui, Beijing, Fujian, Gansu, Guangxi, Guizhou, Hebei, Heilongjiang, Henan,
Hongkong, Hubei, Hunan, Jiangsu, Jiangxi, Jilin, Liaoning, Macao, Nei Mongol,
Ningxia, Shaanxi, Shandong, Shanghai, Shanxi, Sichuan, South China Sea Islands,
Tianjin, Xinjiang, Yunnan, Zhejiang), Taiwan, European Turkey, Iran (N-Iran),
Jammu & Kashmir (Kashmir), USA (introduced) (Arkansas (introduced), Arizona
(introduced), California (introduced), Connecticut (introduced), District of
Columbia (introduced), Delaware (introduced), Illinois (introduced), Indiana
(introduced), Kentucky (introduced), Louisiana (introduced), Massachusetts
(introduced), Maryland (introduced), Missouri (introduced), Mississippi
(introduced), New Hampshire (introduced), New Jersey (introduced), New York
(introduced), Ohio (introduced), Oklahoma (introduced), Pennsylvania
(introduced), Rhode Island (introduced), Tennessee (introduced), Texas
(introduced), Vermont (introduced), Washington State (introduced)), Canada
(introduced) (Ontario (introduced), Quebec (introduced)) as per Catalogue of Life;
 
Fringed water-lily, Yellow floating-heart;
 

Nymphoides peltata (syn. Villarsia nymphaeoides, Fringed Water-lily, Yellow Floating-heart, Water Fringe) is an aquatic plant of the family Menyanthaceae native to Eurasia.  
It has cordate floating leaves that support a lax inflorescence of yellow flowers with fringed petal margins. The fruit is a capsule bearing many flattened seeds with stiff marginal hairs.
The plants are commonly sold for use in ornamental water gardens.
Outside their native range, however, they can escape cultivation and become nuisance noxious weeds.
Flowers of N. peltata are heterostylous and weakly self-incompatible.
(From Wikipedia on 17.7.13)

 Nymphoides peltata is a PERENNIAL.  It is hardy to zone 6. It is in flower from Jul to September, and the seeds ripen from Aug to October. The flowers are hermaphrodite (have both male and female organs) and are pollinated by Bees, Lepidoptera

Water margins of ponds and slow moving water[17].

Europe, including Britain, from Sweden south and east to Spain, N. and W. Asia to Japan

Leaves and leaf stems – cooked as a potherb[2, 178, 179, 183]. The interior of the stem is eaten, it is highly esteemed[145, 178]. The leaves are not very palatable[K]. Flower buds – cooked as a potherb[105, 183]. Seed[178]. No further details are given.

Anthelmintic, diuretic, febrifuge, galactogogue, skin. The fresh leaves are used in the treatment of periodic headaches[145, 178, 240]. The plant is diuretic, febrifuge and refrigerant[218]. It is bruised and used in the treatment of burns, fevers, ulcers, snake bites and swellings[218]. The plant contains rutin, but no details are given of the quantity[218].

(From PFAF ) 

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Nymphoides peltata from Kashmir, characterised by yellow flowers, growing in Dal Lake and ponds. Photographed from artificial lake in Botanical Garden below Cheshmashahi on June 26, 2010.
Common names:
English: Fringed water-lily, Yellow floating-heart
Chinese: Xing cai
Japanese: Asaza
 

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Aquatic Plant for ID : Dal Lake,Srinagar : 24JUN16 : AK-41 : 3 posts by 2 authors. Attachments (3)
Another aquatic plant seen in Dal Lake on the 24th April.

Looks like Nymphaea Species.

Nymphoides peltatum

I hope leaves were less than 10 cm broad

Thanks for the id. Leaves were quite smaller in size.

  

 

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As promised following posting of photos of Trapa, I am attaching some images of Nymphoides peltata taken on Nageen Lake, Srinagar, Kashmir during my last visit to Kashmir.
Stewart found it to be abundant in the Kashmir Valley lakes and ditches, covering hundreds of acres in the Wular Lake. 
Flowers of Himalaya record this from shallow waters & ditches, common in Kashmir Valley; Temperate Eurasia to 1500m.
A submerged aquatic with rounded deeply heart-shaped floating leaves and bright yellow flowers borne above water with rounded petals with fringed margins.
This miniature water-lily is even a British native found in ponds and slow rivers, a local plant.
Belongs to Menyanthaceae family.