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: Poison Sumach

General Information

Toxicodendron vernix is a deciduous shrub or small tree; it usually grows up to 3 metres tall but can reach 6 metres. The short bole can be 35 - 45cm in diameter, often breaking near the ground to form two or three main stems[].
The plant is harvested from the wild for local use as a medicine and source of materials.
Toxicodendron vernix is widespread and while it is possibly declining in parts of its range, it is not thought that any global population decline is likely to meet (or be close to meeting) the threshold for Vulnerable. The plant is classified as 'Least Concern' in the IUCN Red List of Threatened Species(2016)[].

Known Hazards

All parts of plants belonging to the genus Toxicodendron are known to contain resinous phenolic compounds known as urushiols. This is possibly the most toxic member of the genus - direct contacr with the plant, exposure to smoke or fumes from a burning plant or even contact with pets, animals or clothing 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

Eastern N. America - Ontario to Quebec, south to Texas and Florida

Habitat

Wooded swamps, often inundated for part of the year[, , ].

Properties

Conservation Status	Least Concern
Medicinal Rating
Other Uses Rating
Habit	Deciduous Shrub
Height	3.00 m
Pollinators	Bees
Self-fertile	No
Cultivation Status	Wild

Cultivation Details

Toxicodendron vernix is a very cold-hardy plant, able to tolerate temperatures down to around -35°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[, ]. Requires a moist soil[].
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

Poison sumach has occasionally been used medicinally, though it is an extremely poisonous plant and great caution should be exercised. Any herbal use should only be undertaken under the supervision of a qualified practitioner. See also the notes above on toxicity.

The plant has been used in the treatment of fevers, ague, ulcerated bladder, asthma and wasting diseases[]. The plant has been used as a wash to treat foul ulcers[].

Agroforestry Uses:

The flowers are a good source of nectar for bees[].

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 can be made from the sap[].

The sap can be used to make a black varnish that is lustrous and durable[, ]. Used in woodworking[]. The final product is toxic[].

The wood is light, soft, coarse grained[]. It weighs 27lb per cubic foot[].

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[].