frogbit, kilpukka, floating frogbit
Europe, Asia, Africa
Hydrocharis dubia (Blume) Backer
H. morsus-ranae L.
Hydrocharis morsus-ranae is introduced into the United States, Australia, and Canada.
Hydrocharis dubia Backer and H. morsus-ranae are considered weeds in several countries.
creeping, stoloniferous plant with floating and emergent leaves
Perennial. Stolons creeping, originating from leaf axils. Stipules distinctive. Leaves floating or emergent, in rosettes widely spaced along stolon, petiolate; leaf blade ovate to orbicular, venation palmate with cross-veins; base cordate to reniform; margin entire; aerenchyma present at base of leaf. Inflorescence subtended by spathe of 1 or 2 bracts. Flowers unisexual; male flowers sessile, 1-4 per spathe; female flowers pedicellate, solitary; sepals 3; petals 3. Dispersal by seed and stem fragments.
shallow waters of swamps, ponds, and lakes
Hydrocharis dubia is considered threatened in some regions of the world and weedy in others. Hydrocharis chevalieri (de Wildeman) Dandy is a mostly emergent, African species that is not cultivated at present.