There has been considerable uncertainty amongst botanists as to the best way of treating the genus Rhus, with some viewing it in a strict sense as comprising of around 35 species and electing to separate the other species into several distinct genera; whilst others prefer to view the genus in a looser sense being comprised of perhaps 250 species grouped into several subgenera. The genus is treated here in its strict sense, with many other species that have at times been included here being moved to the genera Cotinus, Searsia and Toxicodendron.

Common Name:

General Information

Rhus potaninii is a deciduous tree with an open, rounded head of branches; it usually grows 5 - 9 metres tall, exceptionally to 15 metres or more[, ]. The plant often develops with more than one main stem[].
The plant is harvested from the wild for local use as a medicine and source of materials. Galls produced as a result of insect activity on the plant are widely used medicinally in east Asia, especially in polyherbal preparations. Whilst Rhus chinensis is the main source of these galls, those from this species are also harvested and are often traded[].

Known Hazards

The genus Rhus is being treated in its strict sense here, so it excludes the many species with highly toxic and irritant sap (these are included in Toxicodendron). Although the two genera are very similar, it is relatively simple to distinguish which is which, the poisonous species (Toxicodendron) have axillary panicles and smooth fruits whilst non-poisonous species (Rhus) have compound terminal panicles and fruits covered with acid crimson hairs[, ].
Whilst the genus Rhus in this treatment is generally seen as having a non-toxic sap there are some suggestions that the sap of some species in the genus (including this one) can cause a skin rash in susceptible people.

Botanical References

, ,

Range

E. Asia - central and southern China (Gansu, Henan, Shaanxi, Shanxi, Sichuan, Yunnan.)

Habitat

Hill and mountain forests, thickets; at elevations from 900 - 2,500 metres[, ].

Properties

Medicinal Rating
Other Uses Rating
Habit	Deciduous Tree
Height	6.50 m
Pollinators	Bees
Self-fertile	No
Cultivation Status	Wild

Cultivation Details

Rhus poteninii is a moderatley cold-hardy plant, able to tolerate temperatures down to around -25°c when fully dormant. It grows best in areas with hot summers. In areas with cooler summers (even if the winters are mild), such as the maritime regions of the temperate zone, it often grows poorly, failing to properly ripen its wood and suffering frost damage over the winter[, ]. The young growth in spring is also susceptible to cold and can be damaged by late frosts.
Succeeds in a well-drained fertile soil in full sun[, ].
A very ornamental plant[], but it rarely flowers in Britain[].
Plants have brittle branches and these can be broken off in strong winds[]. Plants are also susceptible to coral spot fungus[]. Plants in this genus are notably resistant to honey fungus[].
A dioecious species - both male and female forms must be grown if fruit and seed are required.

Edible Uses

None known

Medicinal

Galls are produced on the leaves and petioles as a result of activity by the aphid Schlechtendalia chinensis and, to a lesser extent, by Schlechtendalia peitan. These galls are rich in tannins and are often used for their antisepic, astringent, haemostatic and styptic properties. Taken internally they are used to treat a range of conditions including chronic diarrhoea, haemorrhage, persistent cough with blood, spontaneous sweating, night sweats, bloody stool, urorrhoea and bloody sputum[, , ]. They are a frequent ingredient of polyherbal prescriptions for the treatment of various conditions, including diabetes mellitus[, , ].
Applied externally as a wash, powder etc, the galls are used to treat various injuries and conditions including burns, bleeding due to traumatic injuries, haemorrhoids and ulcers in the mouth[].

Other Uses

The leaves are rich in tannin. They can be collected as they fall in the autumn and used as a brown dye or as a mordant[].

An oil is extracted from the seeds[]. It attains a tallow-like consistency on standing and is used to make candles. These burn brilliantly, though they emit a pungent smoke[].

An indelible black ink is obtained from galls on the leaves[, ]. The report does not say if the galls are used before or after the insect leaves them.

Propagation

Seed - best sown in a cold frame as soon as it is ripe. Pre-soak the seed for 24 hours in hot water (starting at a temperature of 80 - 90c and allowing it to cool) prior to sowing in order to leach out any germination inhibitors[]. This soak water can be drunk and has a delicious lemon-flavour. The stored seed also needs hot water treatment and can be sown in early spring in a cold frame[]. When they are large enough to handle, prick the seedlings out into individual pots and grow them on in the greenhouse for their first winter. Plant them out into their permanent positions in late spring or early summer, after the last expected frosts.
Cuttings of half-ripe wood, 10cm with a heel, mid summer in a frame[].
Root cuttings 4cm long taken in December and potted up vertically in a greenhouse. Good percentage[, ].
Suckers in late autumn to winter[].