Poison Sumach
Rhus vernix
Family: Anacardiaceae
What it is like
Rhus vernix is a deciduous Shrub growing to 3 m (9ft 10in). See above for USDA hardiness. It is hardy to UK zone 3 and is not frost tender. It is in flower in July, and the seeds ripen from September to November. The species is dioecious (individual flowers are either male or female, but only one sex is to be found on any one plant so both male and female plants must be grown if seed is required). and is pollinated by Bees. The plant is not self-fertile. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils and prefers well-drained soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It cannot grow in the shade. It prefers moist or wet soil.
Height (m): 3
Where it is found
Wooded swamps, often inundated for part of the year.
Eastern N. America - Maine to Vermont and Ontario, south to Florida, Missouri and Louisiana.
Conservation Status:
Countries/locations it is found in
How it is used
Food
Rating: 0
Oil: Oil
Medicine
Rating: 1
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.
Febrifuge: Reduces fevers.
Miscellany: Various medicinal actions that need more clarification.
Skin: Plants used in miscellaneous treatments for the skin.
Other
Rating:
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. A varnish is obtained from the sap, it is black, lustrous and durable.The final product is toxic. Wood - light, soft, coarse grained. It weighs 27lb per cubic foot.
Dye: Plants that provide dyes.
Ink: Plants that can be used as an ink.
Miscellany: A rag-bag of items that are difficult to categorise.
Mordant: Used for making a dye more permanent, it also affects the colour of the dye.
Oil: Vegetable oils have many uses, as lubricants, lighting, soap and paint making, waterproofing etc. This does not include the edible oils unless they are also mentioned as having other uses.
Varnish: Plants that can be used as a varnish without any special treatment. Does not include varnishes made from oils etc.
Wood: A list of the trees and shrubs that are noted for having useful wood.
How it is grown
Succeeds in a well-drained fertile soil in full sun. Requires a moist soil. The young growth in spring can be damaged by late frosts. 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. Dioecious. Male and female plants must be grown if seed is required.
Propagating it: 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, July/August 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.
Best place to grow: Woodland Garden Sunny Edge; Dappled Shade; Bog Garden;
Habit: Shrub
Hardiness: 3-7
Growth:
Soil: Light (sandy), medium, heavy (clay)
Shade: No shade
Moisture: Moist, wet
Things to keep in mind
This plant contains toxic substances and skin contact with it can cause severe irritation to some people. The sap is extremely poisonous. The sap contains 3-N pentadecycatechnol. Many people are exceedingly sensitive to this, it causes a severe spreading dermatitis. The toxins only reach the skin if the plant tissues have been damaged, but even indirect contact can cause severe problems.
Its other names
Local names
Synonyms
R. venenata. Toxicodendron vernix. (L.)Shafer.