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.
Rhus toxicarium Salisb.
Rhus toxicodendron L.
Toxicodendron quercifolium (Michx.) Greene
Toxicodendron toxicarium Gillis
Rhus acutiloba Turcz.
Toxicodendron toxicodendron (L.) Britton
Common Name: Eastern Poison Oak
Toxicodendron pubescens is a deciduous shrub producing a cluster of slender, erect stems around 60 - 100cm tall. The plant spreads by means of rhizomes, and can form colonies[
The plant is harvested from the wild for local use as a medicine and source of materials.
All parts of plants belonging to the genus Toxicodendron are known to contain resinous phenolic compounds known as urushiols. Direct contacr with the plant, exposure to smoke or fumes from a burning plant or even contact with pets or animals 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[
South-eastern N. America - Kansas to New Jersey, south to Texas and Florida
Dry barrens, pinelands and sands[
]. Open woodlands, scrub oak and pine woodland savannahs, usually on poor, sandy soils[
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Toxicodendron pubescens is a moderately cold-hardy plant, able to tolerate temperatures down to around -15°c when fully dormant. The young growth in spring is more sensitive, however, and can be damaged by late frosts.
Succeeds in a well-drained fertile soil in full sun or light shade[
]. Judging by the plants natural habitat, it should also succeed in poor acid soils and dry soils[
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.
Poison oak 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.
A fluid extract of the fresh leaves is irritant, narcotic, rubefacient and stimulant[
]. It has been used with some success in the treatment of paralysis, obstinate herpatic eruptions, palsy and in various forms of chronic and obstinate eruptive diseases[
A mash of the leaves has been used to treat ringworm[
]. An external application has also been used in the treatment of herpes sores[
A poultice of the plant has been used to treat infectious sores on the lips[
The root has been used to make a poultice and salve in the treatment of chronic sores and swollen glands[
A very commonly used homeopathic remedy with a wide range of applications[
]. It is one of the main treatments for mumps[
], it is also used in a wide range of skin disorders, eye problems, pain etc[
]. The remedy is made from the fresh leaves - these should be harvested of a night-time, during damp weather and before the plant flowers[
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[
The milky juice makes an excellent indelible marking ink for linen etc[
]. It is also used as a varnish for boots and shoes[
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[