Japanese name: アメリカコナギ Scientific name:Heteranthera limosa
[Overview]
An emergent annual 20–30 cm tall, found in rice paddies, shallow ponds and marshes, and wetlands.
The first few leaves after germination and the submerged leaves are broadly linear, but the leaves are usually ovate-lanceolate to ovate, 2–4 cm long and 0.7–3 cm wide, with a base that is not heart-shaped.
The leaf surface is glossy.
The leaf stalk is 9–30 cm long and sheathing at the base.
A flower stalk 2–4 cm long... extends from the leaf sheath and bears one flower at a time.
The flowers are 2.5 cm across, six-petaled, blue to blue-violet or white; blue to blue-violet flowers have a white to yellow marking at the base of the upper petal.
There are 3 stamens and 1 pistil, and the anthers sit directly above the stigma.
Each flower withers in a day.
The fruit is a slender capsule about 2 cm long containing many seeds.
[History]
It was confirmed in the 1970s, and naturalization has been reported in Okayama, Hyogo, Fukuoka and elsewhere.
