Vaccaria hispanica (cowherb, "Dokanso")

Japanese name: ドウカンソウ （道灌草）
Scientific name: Vaccaria hispanica

[Overview]
An annual or biennial 30–60 cm tall.
The whole plant is hairless and tinged with bluish gray.
The stem branches in the upper part.
Leaves are simple and opposite, broadly ovate to lanceolate, 2–8 cm long, entire, and without leaf stalks.
The flowers are 5-petaled, 1.5 cm across, and reddish purple to white.
There are 10 stamens.
The calyx tube is about 1.5 cm long, cylindrical and swollen at the base, with 5 ridges projecting like wings.
The fruit is an ovoid capsule enclosed in the calyx tube.

[History]
It was introduced as an ornamental in the Edo period.

[Uses]
The seeds are used medicinally.

[Cultivation]
Propagate from seed.
It prefers a sunny, well-drained site.
It dislikes heat and humidity, so take care not to plant it too densely.
Take care not to overwater; water thoroughly when the soil surface dries.
Too much fertilizer makes it leggy and prone to falling over, so if fertilizer is applied at planting, no further feeding is particularly necessary.
Tall plants fall over easily, so it is good to set up stakes.
There are no particular pests or diseases.

[Notes]
The Japanese name is said to come from its cultivation in a medicinal herb garden on Dokanyama in the suburbs of Edo during the Edo period.

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