- Scientific Name: Trapa natans L.
- Ref: Sp. Pl.:120. 1753
- Synonyms:
- Trapa acicularis V.N.Vassil.
- T. alatyrica Sprygin ex V.N.Vassil.
- T. algeriensis V.N.Vassil.
- T. amurensis Flerow
- T. amurensis var. bispinosa Flerow
- T. annosa Jankovic
- T. araborum V.N.Vassil.
- T. arcuata S.H.Li & Y.L.Chang
- T. astrachanica (Flerow) N.A.Winter
- T. astrachanica var. caspica (V.N.Vassil.) Tzvelev
- T. bicornis var. taiwanensis (Nakai) Z.T.Xiong
- T. borysthenica V.N.Vassil.
- T. brevicarpa Jankovic
- T. carinthiaca (Beck) V.N.Vassil.
- T. caspica V.N.Vassil.
- T. caucasica Flerow
- T. colchica Albov
- T. conocarpa var. pyramidalis (V.N.Vassil.) Tzvelev
- T. conocarpa var. suecica (Nath.) Tzvelev
- T. cruciata (Glück) V.N.Vassil.
- T. danubialis Dobrocz.
- T. europaea Flerow
- T. fastigiata P.Vassil.
- T. flerovii Dobrocz.
- T. grozdovii V.N.Vassil. ex V.N.Tikhom.
- T. hungarica Opiz ex Nyman
- T. jankovicii Tacik
- T. kasachstanica V.N.Vassil.
- T. kazakorum P.Vassil.
- T. komarovii V.N.Vassil.
- T. laevis C.Presl ex Nyman
- T. longicarpa Jankovic
- T. longicornis V.N.Vassil.
- T. macrorhiza Dobrocz.
- T. maeotica Woronow
- T. maleevii V.N.Vassil.
- T. manshurica Flerow
- T. maximowiczii Korsh.
- T. media (Glück) V.N.Vassil.
- T. metschorica P.Vassil.
- T. muzzanensis Jäggli
- T. numidica V.N.Vassil.
- T. okensis P.Vassil.
- T. pectinata V.N.Vassil.
- T. pseudocolchica V.N.Vassil.
- T. pseudorossica V.N.Vassil.
- T. pyramidalis V.N.Vassil.
- T. quadricornis Stokes
- T. quadrispinosa Roxb.
- T. raciborskii Jent.-Szaf. ex Tacik
- T. rossica V.N.Vassil.
- T. saissanica (Flerow) V.N.Vassil.
- T. sajanensis P.Vassil.
- T. septentrionalis V.N.Vassil.
- T. sibirica Flerow
- T. spryginii V.N.Vassil.
- T. taiwanensis Nakai
- T. tranzschelii V.N.Vassil.
- T. turbinata P.Vassil.
- T. ucrainica P.Vassil.
- T. uralensis P.Vassil.
- T. verbanensis De Not.
- T. wolgensis P.Vassil.
- English Common Name: water caltrop, water chestnut
- Chinese Common Name: 欧菱 Ōu líng
- Japanese Common Name: オニビシ [鬼菱] onibishi
- Family: Lythraceae
- Genus: Trapa
- Distribution: Slow-moving rivers, lakes, swamps, ponds, also widely cultivated in China; near sea level to 2700 m. Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hainan, Hebei, Heilongjiang, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Jilin, Liaoning, Nei Mongol, Shaanxi, Shandong, Sichuan, Taiwan, Xinjiang, Xizang, Yunnan, Zhejiang [India, Indonesia, Japan, Korea, Laos, Malaysia, Pakistan, Philippines, Russia, Thailand, Vietnam; Africa, SW Asia (Iran), Europe; widely cultivated in tropical and subtropical Asia; naturalized in Australia and North America].
- Note: Generally the Japanese common name オニビシ referred to Trapa natans L., in a narrow sense, オニビシ specifically refer to Trapa natans var. japonica Nakano.
Stem 2.5-6 mm in diam. Petiole (2-)5-18 cm, stout, ± swollen distally, pubescent; leaf blade glossy and dark green adaxially, greenish purple abaxially, often with colored spots between veins, deltoid-rhombic to oblate-rhombic, 4-6 × 4-8 cm, abaxially pubescent, adaxially glabrous, base broadly cuneate, margin irregularly dentate distally. Petals white, 7-10 mm. Fruit turbinate to shortly rhombic, 1.8-3 × 2-4.5 × 1-2.8 cm, (0-)2-4-horned, crest a prominent bulge to a thin rib, crown tetragonal to rounded, or dome-shaped, rarely crownless, 1-8(-11) mm, beak conic or a tuft of hairs; horns horizontal, ascending, or recurved, flat-triangular or broadly conic, 2-3.5 cm, apex barbellate or cultivated without barbs. Fl. May-Oct, fr. Jul-Nov. 2n = 44*, 46*, 48*, 76*, 90*, ?96. (Flora of China)
