Rhabarbarum ribes (L.) Moench
Rheum ribes is a herbaceous perennial plant growing from a stout, woody, rhizomatous rootstock; it produces a basal clump of leaves arounf 14 - 42cn long and 18 - 70cm wide on stout petioles; the plant flowers in the summer, producing stout many-branched flowering stems up to 150cm tall[
The plant is harvested from the wild for local use as a food. It was widely used in antiquity in Arabia and in Iran
as a food and medicinal plant. The species is little known in cultivation, even though it is particularly promising[
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[
W. Asia - Turkey, Lebanon, Syria, Israel, Palestine, Iraq, Iran, Caucasus, Afghanistan, Palestine.
Dry gorges among rocks, at elevations from 2,300 - 2,700 metres[
]. Clayey slopes and ravines in the subalpine zone[
Rheum ribes is a moderately cold-hardy plant, tolerating temperatures in winter that can fall to about -20°c according to one report[
], whilst another report says that plants are somewhat tender in Britain[
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. This species is best grown in a dry position, where it can be very long-lived[
Plants in this genus seem to be immune to the predations of rabbits[
Hybridizes freely with other members of this genus[
Leaf stem - cooked[
]. Eaten raw by the local people[
]. The juice containing about 0.5%t of potassium oxalate imparts a very pleasant taste[
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.