Acmella oleracea (toothache plant, "Kibanaorandasennichi")

Japanese name: キバナオランダセンニチ
Scientific name: Acmella oleracea

[Overview]
A perennial 30–40 cm tall, treated as an annual in Japan.
The leaves are simple and opposite, ovate to triangular-ovate, with toothed margins.
They have leaf stalks.
The cylindrical flower heads consist only of yellow tubular florets, numbering in the hundreds.
In some plants the tips of the flower heads turn brown, while in others the whole head is yellow.
The flower heads are rounded at the tip and become longer as flowering progresses.
The fruit is an achene.

[History]
It was introduced to Japan in the 13th year of the Tenpo era.

[Uses]
The leaves and flowers are used as a folk medicine, and because of their pungency they are also used as a spice.

[Cultivation]
Propagate from seed.
Sow after frost has ceased; the seeds need light to germinate, so cover them with only a very thin layer of soil and water from the bottom.
It prefers fertile soil that is sunny and well drained.
For potted plants, water thoroughly when the soil surface dries; for plants in the ground, rainfall is sufficient unless sunny weather continues and the soil becomes dry.
Apply basal fertilizer, and during flowering place slow-release fertilizer on the soil about once a month.
There are no particular pests or diseases.

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