Japanese name: コオニビシ（小鬼菱） Scientific name:Trapa natans var. pumila
[Overview]
An aquatic annual growing in ponds and marshes.
The stem is long and extends to the water surface, and bears submerged leaves from the nodes that are fully pinnately divided and root-like.
The floating leaves are simple and alternate, clustered at the stem tip and spreading radially on the water surface; they are 2–5 cm long and 2–8 cm wide, triangular to triangular-rhombic, with triangular teeth on the upper margin.
The leaf stalk is long and swollen in the middle, serving as a float.
The flowers are solitary in the leaf axils and are white, 4-petaled, about 1 cm across.
The fruit is a slightly flattened, inverted-triangular nut with 4 sharp spines in total, one on each of the left and right sides and both flanks.
The spines are developed from the 4 sepals.
[Notes]
The scientific name was described as a variety of Onibishi, but it is included in Hishi.
