There has been considerable uncertainty amongst botanists as to the best way of treating the genus Toxicodendron, with some viewing it as a genus distinct from Rhus, whilst others see insufficient differences and lump the two genera under Rhus. Toxicodendron is treated here as distinct, with two of the major differences from a gardener’s viewpoint being that Toxicodendron has a toxic sap (not toxic in Rhus) and the fruits have a thick, waxy mesocarp.

Common Name:

General Information

Toxicodendron wallichii is a deciduous tree with a sparse, open crown; it usually grows around 5 - 7 metres tall, but can reach 15 metres[, ].
The plant is harvested from the wild for local use as a medicine and source of materials.

Known Hazards

Species in the genus Toxicodendron are known to contain resinous phenolic compounds known as urushiols that can cause severe skin problems in humans. Direct contacr with the plant, exposure to smoke or fumes from a burning plant or even contact with pets, animals or cothing that have touched the plant can cause severe allergic dermatitis in some individuals. There is usually a latent period of about 12 - 24 hours from the moment of contact, this is followed by a reddening and severe blistering of the skin. Even plant specimens 100 or more years old have been known to cause problems[].
The plant does not cause skin problems with wildlife or livestock - the foliage and fruits are eaten by several other species of animals and birds - though some pets are sensitive to it[].

Botanical References

, ,

Range

E. Asia - southern China (Guangxi, Xizang, Yunnan), northern India, Nepal

Habitat

Shady and open places in forests and shrubberies; at elevations from 300 - 2,500 metres[, ].

Properties

Medicinal Rating
Other Uses Rating
Habit	Deciduous Tree
Height	8.00 m
Pollinators	Bees
Self-fertile	No
Cultivation Status	Wild

Cultivation Details

Toxicodendron wallichii is not a very cold-hardy plant, being able to tolerate short-lived temperatures falling down to around -10°c when fully dormant. The young growth in spring, however, is more sensitive and can be damaged by late frosts.
Species in this genus generally succeed in a well-drained fertile or moderately fertile soil in full sun or light shade[, ].
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[].
Many of the species in this genus, including this one, are highly toxic and can also cause severe irritation to the skin of some people, whilst other species are not poisonous. It is relatively simple to distinguish which is which, the poisonous species have axillary panicles and smooth fruits whilst non-poisonous species have compound terminal panicles and fruits covered with acid crimson hairs[, ]. The toxic species are sometimes separated into their own genus, Toxicodendron, by some botanists[].
A dioecious species - both male and female forms must be grown if fruit and seed are required.

Edible Uses

None known

Medicinal

The juice of the leaves is a corrosive vesicant[].

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[].
The leaf juice is rubbed onto thread to strengthen it[]. (This is probably due to the presence of tannins which would act as a preservative[].)

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[]. The globose drupe is 5 - 10mm in diameter with a thick, waxy mesocarp[].

A lacquer is obtained from the sap of this plant[].

Wood. Used for tools, musical instruments[, , ]. It is also used to make the handle of the Khukuri, the Nepalese curved knife[].

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[]. 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[].