Monochoria vaginalis (Burm. f.) K. Presl ex Kunth
Synonym(s): heartshape false pickerelweed, heartshape falsepickerelweed, pickerel weed

Monochoria vaginalis is an aquatic herbaceous plant native to temperate and tropical Asia. Plant size, leaf shape, and flower number in M. vaginalis are highly dependent on the amount of water available. It can be annual or perennial. It has a short rhizome. M. vaginalis can grow from 4-20 in. (10-50 cm) tall and is stemless.
Two types of leaves are seen. The sessile leaves are up to 2 in. (5 cm) long. The blade is linear with an acuminate apex. Petiolate leaves are cordate with a soft hollow petiole from 3-11 in. (7-28 cm) long.
The flowers of M. vaginalis are few to numerous in racemes 0.79-1.6 in. (2-4 cm) long. In California racemes usually bear 2-8 flowers. The peduncles emerge from the sheath of the upper-most leaf.
Fruits are ellipsoid 3-valved capsules about 0.4 in. (1 cm) long. The numerous oblong seeds have 8-12 longitudinal ribs.
Ecological Threat
Monochoria vaginalis is listed as a Federal Noxious Weed. It has been reported in California and Hawaii. It is often seen as a weed in rice fields.

Identification, Biology, Control and Management Resources