Heartleaf false pickerelweed is a small Asian aquatic plant and one of the major weeds of rice paddies across Asia. In the US it is a ; it has turned up in California's rice country (records from the 1950s to the 1990s) and in Hawaii.
Appearance
- Appearance
- A shiny green herb usually about 4–20 in (10–50 cm) tall, with size varying a lot with water and growing conditions; usually annual, but can live longer in permanently flooded spots.
- Leaves
- Submerged young leaves are narrow and lance-shaped; later leaves on long, hollow stalks are heart-shaped, up to about 5 in (12 cm) long.
- Flowers
- Small spikes of 3–25 light blue to purple-blue flowers, each a little over 0.4 in (1 cm) long. Flowers often open underwater.
- Fruit
- A capsule about 0.4 in (1 cm) long packed with tiny seeds.
Look-alikes
DucksaladHeteranthera limosa
Ducksalad flowers come one at a time from a leafy sheath, with narrow, spreading petals, and are often white as well as blue. Heartleaf false pickerelweed carries small clusters of 3–25 blue flowers. Plants without flowers are hard to tell apart.
Why they get mixed upBoth are small rice-field weeds with blue flowers; California growers have called a blue-flowered ducksalad 'Monochoria'.
Where it lives
- Typical habitats
- rice fields
- ponds
- slow streams
- marshes
- Range
- Native to much of Asia and many Pacific islands, and introduced elsewhere. In the US it has been recorded in California and Hawaii; the California herbarium records (1954 to 1991) come almost entirely from Butte County, mostly around the Rice Experiment Station near Biggs.
- Preferred conditions
- Shallow, still or slow-moving water, rooted in the mud.
Name and classification
- About the name
- Long known as Monochoria vaginalis; recent classifications move it into Pontederia along with water hyacinth and pickerelweed.
Conservation
- IUCN Red List
- LCLeast ConcernLow risk of extinction
- Status
- Listed on the USDA Federal Noxious Weed List. California treats it as a quarantine pest, and several other states also regulate it.
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