Monochoria vaginalis
Heart shape false pickerelweed
(c) Cheng-Te Hsu, some rights reserved (CC BY), uploaded by Cheng-Te Hsu · licence
Family: Pontederiaceae · Type: Herb · Not Native
Monochoria vaginalis (Heart shape false pickerelweed) is a non-native California herb in the Pontederiaceae family, recognized by Asian rice field weed with unique underwater flowering behavior, very limited California distribution.
Heart shape false pickerelweed is a naturalized perennial found in the Sacramento Valley in rice fields at elevations above 100 meters. Flowering in September, this aquatic plant produces blue flowers opening under water, with perianth parts less than 2 centimeters long. Growing with stems exceeding 12 centimeters tall, it spreads through wet agricultural landscapes. Its leaves feature distinctive heart-shaped blades 2.5 to 11 centimeters long, supported by petioles ranging from 4 to 70 centimeters. The inflorescence extends more than 5 centimeters with a few scattered flowers.
Identification and appearance
Key characters: Asian rice field weed with unique underwater flowering behavior, very limited California distribution
Habitat and range
Habitat: Uncommon. Rice fields
Elevation: > 100 m
Outside California: native to tropical Australia, Asia
Bloom period
Monochoria vaginalis blooms Sep.
How to tell it apart
vs Eichhornia: Monochoria is rooted with heart-shaped leaves; Eichhornia floats freely with balloon-like leaf stalks.; vs Heteranthera: Monochoria has six stamens and short bell flowers; Heteranthera has three stamens and long trumpet flowers.
Frequently asked questions
Is Monochoria vaginalis native to California?
No. Monochoria vaginalis is not native to California (recorded as not native).
When does Monochoria vaginalis bloom?
Monochoria vaginalis blooms Sep.
What plant family does Monochoria vaginalis belong to?
Monochoria vaginalis is in the Pontederiaceae family, genus Monochoria.
What habitat does Monochoria vaginalis grow in?
Monochoria vaginalis grows in Uncommon. Rice fields.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · CalPhotos
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.