Species in the genus Ammannia:

Ammannia auriculata / Nangokuhimemisohagi ナンゴクヒメミソハギ

Ammannia auriculata, an annual herb reportedly inhabiting North America, recently grew wild in western Japan. Stems rise 20-80cm, with wings on ridges. Leaves are of opposite phyllotaxis,2-8cm long, in the shape of a broad linear, with bases somewhat jutting out in a hastate way. Flowers with four petals, red-purple, 1-5 in number, set themselves on the tips of 3-10cm long peduncles; pedicels measure 2-5mm long. Bloom time: August-October.