Sparganium fallax ("Yamatomikuri")

Japanese name: ヤマトミクリ （大和実栗）
Scientific name: Sparganium fallax

[Overview]
A perennial 50–120 cm tall, growing in colonies in shallow water of lakes, ponds, irrigation ponds and rivers.
It is common in still water and somewhat rare in flowing water.
The rhizome creeps horizontally.
The leaves are alternate in two rows and linear, 4–10 mm wide, with a ridge on the underside, so the cross section is triangular.
The leaf base forms a sheath.
The inflorescence is unbranched and bears spherical flower heads (capitula).
On the lower part of the main axis of the inflorescence, 3–6 female heads are borne somewhat apart from one another, and the stalk of each female head is fused to the main axis for part of its length.
When the fused part is long, the head appears to be borne on the side opposite the bract.
The part of the main axis bearing the female heads often bends in a zigzag.
On the upper part of the main axis, 5–9 male heads are borne apart from one another.
The fruit is spindle-shaped, 5–6 mm long, and forms an aggregate fruit 1.5–2 cm across.
The fruit is a nut; the outside of the pericarp is soft and spongy, and the inside is hard.

[Notes]
It is common in western Japan, and the Japanese name was given in the sense that it is common in the Yamato region.
Mikuri comes from the aggregate fruit resembling a chestnut burr.

View this page in Japanese (日本語)