Arisaema japonicum ("Mamushigusa")

Japanese name: マムシグサ （蝮草）
Scientific name: Arisaema japonicum

[Overview]
A perennial up to 120 cm tall, found in forests and at forest edges.
It has an oblate corm underground, with many small cormlets attached.
The sheathing leaves and the lower part of the petioles form a pseudostem, which usually has purplish brown spots.
There are 2 leaves, each with 9–17 leaflets arranged pedately (like a bird's foot).
The leaflets are lanceolate to elliptic with pointed tips; the margins are entire, but sometimes finely toothed.
The flower stalk is erect, taller than or about the same height as the petioles, and bears a spadix at the tip.
The appendage at the tip of the inflorescence is club-shaped and erect.
The spadix is enclosed in a spathe.
The spathe is pale greenish brown to purplish brown with white longitudinal stripes; the limb is triangular-ovate to narrowly ovate with a pointed tip.
The fruit is an ovoid berry that ripens red.
The plant is dioecious; young plants are male and change to female as they grow.

[Uses]
It is poisonous, but the corm is used medicinally.

[Cultivation]
Propagate from seed or by dividing the corms.
When growing from seed, wash fully ripe fruits to remove the pulp and sow them immediately.
It prefers shady, moist places.
Strong sunlight damages the leaves.
It dislikes dryness, so take care that it does not run short of water during the growing period, but too much moisture also causes root rot.
Do not let the soil dry out completely even during dormancy.
It likes fertilizer, so give liquid fertilizer once every 2 weeks during the growing period.
Pests and diseases include soft rot, southern blight, scale insects, aphids and slugs.

[Notes]
The Japanese name compares the mottled pattern of the pseudostem to a mamushi (a Japanese pit viper).

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