Common Name:

General Information

Rheum coreanum is a herbaceous perennial plant growing from a stout, woody, rhizomatous rootstock; it produces a basal clump of leaves around 30 - 60cm in diameter on stout petioles that are up to 50cm long; the plant flowers in the summer, producing flowering stems around 150 - 200cm tall[].
The plant is harvested from the wild for local use as a medicine. It is one of several species of Rheum used in Japan for medicinal purposes and is included in the Japanese Pharmacopoeia[], It is cultivated for medicinal use in colder regions of Japan[].

Known Hazards

The plant, but especially the leaf blades, contains several toxic compounds, particularly anthraquinone glycosides, but also soluble oxalates and calcium oxylate crystals[, , ]. At lower doses these can cause abdominal cramps, burning of the mouth and throat, headache, weakness, nausea and vomiting. In larger, quantities it can lead to coma and death, though generally very large quantities need to be eaten for the plant to be fatal.
The leaf stems (petioles) have much lower quantities of toxins and, in several Rheum species are a commonly eaten food. The main caution here are the levels of oxalates. These can lock up certain minerals (especially calcium) in the body, leading to nutritional deficiency. Cooking the plant will reduce the concentration of oxalic acid. People with a tendency to rheumatism, arthritis, gout, kidney stones or hyperacidity should take especial caution if including this plant in their diet since it can aggravate their condition[].

Botanical References

Range

E. Asia - N. Korea.

Habitat

Alpine grass areas[].

Properties

Medicinal Rating
Habit	Perennial
Height	1.50 m
Pollinators	Wind
Cultivation Status	Cultivated, Wild

Cultivation Details

Rheum coreanum is a moderately cold-hardy plant, tolerating winter temperatures that can fall to about -20°c[].
Rheum species generally prefer a deep, fertile, moderately heavy, humus rich, moisture retentive, well-drained soil in sun or semi-shade[]. They grow well along the woodland edge or amongst large shrubs[]. They succeed in heavy clay soils.
Plants in this genus seem to be immune to the predations of rabbits[].
Hybridizes freely with other members of this genus[].

Edible Uses

None known

Medicinal

The root is laxative and stomachic[].

This is one of several species used medicinally in Japan

Other Uses

None known

Propagation

Seed - best sown in autumn in a shaded cold frame[]. The seed can also be sown in spring in a cold frame. When large enough to handle, prick the seedlings out into individual pots and grow them on in the greenhouse or cold frame for their first winter, planting them out in the spring.
Division in early spring or autumn[, ]. Divide up the rootstock with a sharp spade or knife, making sure that there is at least one growth bud on each division. Larger divisions can be planted out direct into their permanent positions. We have found that it is better to pot up the smaller divisions and grow them on in light shade in a cold frame until they are well established before planting them out in late spring or early summer.