Japanese name: コマツヨイグサ（小待宵草） Scientific name:Oenothera laciniata
[Overview]
A biennial 20–60 cm tall, found on dry sandy ground, river beds, seashores, farmland and similar places.
The stem rises obliquely or creeps, branching well from the base and spreading.
It sprouts in autumn and overwinters as a rosette.
There are basal leaves and leaves on the stem; the basal leaves have petioles.
The stem leaves are simple and alternate, oblong to lanceolate, 2–10 cm long and 0.4–3.5 cm wide, and are usually pinnately divided.
The leaves on the upper part of the stem are not pinnately divided and have shallow wavy teeth.
The flowers are solitary in the leaf axils and are pale yellow, 4-petaled, up to about 4 cm across in larger ones.
The flowers open from evening and wither the next day, turning red as they wilt.
The fruit is a cylindrical capsule with short upward-pointing hairs.
[History]
It is said to have arrived in Japan around the 1910s.
[Notes]
It is designated as an invasive alien species requiring caution under the Invasive Alien Species Act.
