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Common Name: Matted St. John's Wort
Hypericum japonicum is a Annual/Perennial up to 0.50 metres tall.
It has medicinal uses.
The plant is suspected of causing photo-sensitization[
]. Feeding trials to livestock in New Zealand have shown that it is non-toxic[
E. Asia - China, Japan to Australia - Victoria, Tasmania, and New Zealand.
Wet places in lowland, C. and S. Japan. Rice fields, ditches, marshes, grasslands and waste places from sea level to around 3000 metres[
Easily grown in any reasonably good well-drained but moisture retentive soil[
]. Succeeds in sun or semi-shade but flowers better in a sunny position. This species is found in the wild in wet soils.
A very variable species[
The plant is alterative, antiphlogistic, astringent, depurative, febrifuge and vulnerary[
]. It is decocted with water for use[
]. It is used in the treatment of asthma and dysentery, acute hepatitis, pain in the liver region, appendicitis, boils and abscesses and has also been used as a styptic[
]. The plant has also shown antitumour activity[
Seed - sow spring in a cold frame. When they are large enough to handle, prick the seedlings out into individual pots and plant them out in late spring.
It might also be worthwhile trying an outdoor sowing in mid spring.