mostly New World, some introduced to Old World
Sagittaria cuneata E. Sheld.
S. isoetiformis J.G.Sm.
S. lancifolia L.
S. latifolia Willd.
S. montevidensis Cham. & Schltdl.
S. platyphylla (Engelm.) J.G. Sm.
S. sagittifolia L.
U.S. Federal Noxious Weed: Sagittaria sagittifolia
Identification: The often narrowly sagittate leaf blade is a distinguishing character of S. sagittifolia. Achene (fruit) characters can help in distinguishing among Sagittaria species. In particular, relative widths of the achene wings, presence or absence of a wing on achene faces, and the relative position and orientation of the achene beak.
S. subulata (L.) Buchenau
Numerous introductions of various species throughout the world.
Sagittaria guayanensis Kunth is introduced into the United States.
S. latifolia is introduced into Hawaii (United States) and Europe.
S. montevidensis is introduced into Australia, New Zealand and the United States.
S. platyphylla is introduced into Australia, New Zealand and Europe.
S. rigida Pursh is introduced into Europe.
S. sagittifolia is reported from Australia and New Zealand, but is most likely misidentified.
S. subulata is introduced into Indonesia and Europe.
S. sagittifolia is an aquatic weed on the U.S. federal noxious weed list. Several species are known as weeds in rice fields, including S. montevidensis, S. platyphylla, and S. subulata.
Perennial or annual. Plants typically submerged when juvenile, emergent when mature. Stem compact, stoloniferous. Leaves submersed, floating and emergent, in a basal rosette; petiole present or absent, elongate (when present); leaf blade linear, lanceolate to deeply sagittate, venation parallel, pinnate, or palmate; margin entire. Inflorescence erect, a peduncle bearing whorled rays of flowers. Sepals 3, green; petals 3, white, pink, yellow, or white with basal purple spot. Fruit a winged and beaked achene. Dispersal by stolon and achene.
A New World genus spreading throughout the Old World. The taxonomy of the genus is problematic, with little consensus from recent revisions.