Arthraxon hispidus (small carpetgrass, "Kobunagusa")

Japanese name: コブナグサ （小鮒草）
Scientific name: Arthraxon hispidus

[Overview]
An annual 20–50 cm tall, commonly found on paddy banks, fallow fields, wetlands, and damp roadsides and meadows, often growing in colonies.
The stem is slender; the lower part branches freely from the base, creeps along the ground and roots at the nodes, while the upper part rises and branches.
The stem nodes are hairy.
Leaves are simple and alternate, 2–6 cm long and 1–2.5 cm wide, ovate to ovate-lanceolate, with a pointed tip, a strongly wavy margin, and a base that deeply clasps the stem.
Coarse hairs grow on the leaf sheath and on the margin of the leaf base.
At the stem tip, 3–20 branches (racemes) emerge in a palmate arrangement, bearing sessile spikelets.
The spikelets consist of 2 florets and are lanceolate and pale green, often tinged with purple; they have bristles and sometimes awns.
The amount of hair, the color and length of the spikelets, and the length of the awns vary.

[Uses]
It is used as a yellow dye, and on Hachijojima it is used to dye Kihachijo (a traditional textile).
It is also used medicinally.

[Cultivation]
Propagate from seed.
It is hardy and, if the environment suits it, grows well even when left alone, and also spreads readily from self-sown seed.
It prefers a sunny place with moderate moisture.

[Notes]
The Japanese name compares the shape of the leaves to a small crucian carp.

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