Monochoria vaginalis

Monochoria vaginalis or Konagi (scientific name: Monochoria vaginalis) is an annual or perennial grass native to Southeast Asia in the genus Monochoria of the family Pontederiaceae.
It was brought to Japan during the Yayoi period (710-794) and used as a vegetable and medicinal herb. It grows wild in rice paddies and other watery areas throughout Japan, but is now frowned upon as a weed that invades rice paddies and other water bodies and inhibits the growth of rice plants.
The leaves are dark green and glossy, and transform from lanceolate to ovate as they grow.
The inflorescences bear 3 to 25 small blue-purple flowers that bloom simultaneously in the water, each wilting within a day.

Common name: Monochoria vaginalis, scientific name: Monochoria vaginalis, Original: Southeast Asia, distribution: Japan, habitat: aquatic (paddy fields and other moist places), grass length: 20-30 cm, petiole: 20-30 cm. Flowering season: August to October, Inflorescence: raceme, flower color: blue, purple, number of petals: 6, flower diameter: 1.5 to 2 cm, Fruiting season: October to November, Fruit type: capsule, Fruiting site: underwater.