Trapa japonica
Taxonomy and growth
Uses
Toxicity
Toxicity warning. The historical record reports a hazard for this plant. Do not use it to decide which parts are safe to eat or use medicinally.
We have no specific information for this species, but the raw seed of several members of this genus contains toxins. However, these are destroyed in the cooking process[2][3].
Edible uses
Seed - raw or cooked[1]. Some caution is advised, see the notes above on toxicity.
- Plant part
- Seed
Environment
- Range
- Europe to E. Asia.
- Habitat
- Lakes and ponds all over Japan[4].
- Light
- full sun
- Shade tolerance
- no shade
- Water
- aquatic
- Soil textures
- sandy, loamy, clay
- Soil pH
- acid, neutral
- Tolerates Nutritionally Poor Soil
- No
- Drought
- intolerant
Propagation
Seed - harvest in late summer and store overwinter in a jar of water in a cold but frost-free place. The seed quickly loses its vitality if it is allowed to become dry. Sow in spring, placing one seed in each pot and submerging them under a few centimetres of water.
Cultivation
We have very little information on this species and do not know if it will be hardy outdoors in Britain. However, judging by the plants native range, it is likely to succeed outdoors at least in the warmer areas of the country. The following notes are based on the general needs of the genus. An aquatic plant, floating by means of inflated petioles, it succeeds in still or slowly-flowing water requiring a position in full sun and a slightly acidic water with a rich planting medium[2]. Plants require a high summer temperature in order to perform well, they are not frost hardy[3].
References
Tanaka. T. Tanaka's Cyclopaedia of Edible Plants of the World. Keigaku Publishing 1976-00-00
Huxley. A. The New RHS Dictionary of Gardening. 1992. MacMillan Press 1992-00-00 ISBN 0-333-47494-5
Larkcom J. Oriental Vegetables John Murray 1991-00-00 ISBN 0-7195-4781-4
Ohwi. G. Flora of Japan. (English translation) Smithsonian Institution 1965-00-00