Oenanthe javanica subsp. javanica ("Seri")

Japanese name: セリ （芹）
Scientific name: Oenanthe javanica subsp. javanica

[Overview]
A wetland perennial growing 20–80 cm tall.
It is found in wet ground, on the banks between rice fields, and along small streams.
The whole plant has a distinctive fragrance.
It extends thick white underground stems and spreads by producing new shoots from the nodes.
The stem branches somewhat.
The leaves are 1- to 2-times ternately compound, and the leaflets are ovate.
The leaf margins are serrate.
Compound umbels 4–8 cm across at the stem tips bear many small flowers.
The flowers are white with 5 petals, about 3 mm across.
The fruit is an oval mericarp that floats on water and is dispersed by the current.

[History]
It is praised in poems in the Man'yoshu, and the Engishiki (927) records its cultivation.

[Uses]
It has long been used as food and medicine, and as one of the Seven Herbs of Spring it is put into nanakusa-gayu (seven-herb rice porridge).

[Cultivation]
Propagate from seed or by division.
It prefers a sunny place, but it is weak against dryness and heat, so in summer move it to a well-ventilated place in partial shade.
It prefers soil that retains water well.
Water thoroughly when the soil surface begins to dry.
For potted plants, watering from below with the pot standing in water is also fine.
It will grow even if you simply place the roots of seri bought for eating in water.
When watering from below or growing hydroponically, change the water frequently so that it does not spoil.
Little fertilizer is needed.
Aphids are a pest.
If the branches become crowded, they become stuffy and pests and diseases may occur.

[Notes]
One theory holds that the name derives from the plants growing in competition with one another in one place.
It resembles the poisonous water hemlock (Doku-zeri), so care is needed when gathering it in the wild.

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