Practical
Plants

Rhus toxicodendron

Eastern Poison Oak

a perennial woody deciduous member of the Rhus genus in the family Anacardiaceae.

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Taxonomy and growth

Genus
Rhus
Life cycle
perennial
Foliage
deciduous
Woodiness
woody
Height
0.6 m
Spread
1 m
Fertility
Self sterile, Bees
Flower type
dioecious
Pollinators
Bees

Uses

Toxicity

Toxicity warning. The historical record reports a hazard for this plant. Do not use it to decide which parts are safe to eat or use medicinally.

This section contains historical Plants For A Future notes marked noncommercial.

This plant contains toxic substances and skin contact with it can cause severe irritation to some people[2]. The sap is extremely poisonous[2]. 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[4].

Medicinal uses

Historical medicinal uses. These records describe reported uses. They do not establish safety or effectiveness. Ask a qualified health professional before using any plant medicinally.

This section contains historical Plants For A Future notes marked noncommercial.

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[8]. 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[8]. A mash of the leaves has been used to treat ringworm[5]. An external application has also been used in the treatment of herpes sores[5]. A poultice of the plant has been used to treat infectious sores on the lips[7]. The root has been used to make a poultice and salve in the treatment of chronic sores and swollen glands[7]. A homeopathic remedy is made from the fresh leaves[6]. These should be harvested of a night-time, during damp weather and before the plant flowers[6]. This remedy has a wide range of applications and is one of the main treatments for mumps[6], it is also used in a wide range of skin disorders[8].

Product or use
Homeopathy
Product or use
Irritant
Product or use
Narcotic
Product or use
Parasiticide
Product or use
Rubefacient
Product or use
Salve
Product or use
Stimulant

Material uses

This section contains historical Plants For A Future notes marked noncommercial.

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[3]. An oil is extracted from the seeds[8]. It attains a tallow-like consistency on standing and is used to make candles. These burn brilliantly, though they emit a pungent smoke[8]. The milky juice makes an excellent indelible marking ink for linen etc[8][2]. It is also used as a varnish for boots and shoes[8].

Product or use
Dye
Product or use
Ink
Product or use
Mordant
Product or use
Oil
Product or use
Tannin
Product or use
Varnish

Environment

Range
South-eastern N. America - New Jersey to Delaware, south to Georgia, Alabama and Texas.
Habitat
Dry barrens, pinelands and sands[9].
Light
full sun
Shade tolerance
no shade
Water
moderate
Hardiness
Zone 7+
Soil textures
sandy, loamy, clay
Soil pH
acid, neutral, alkaline
Drainage
well drained
Tolerates Nutritionally Poor Soil
No
Drought
intolerant

Propagation

This section contains historical Plants For A Future notes marked noncommercial.

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[4]. The stored seed also needs hot water treatment and can be sown in early spring in a cold frame[4]. 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[4]. Root cuttings 4cm long taken in December and potted up vertically in a greenhouse. Good percentage[10][4]. Suckers in late autumn to winter[4].

Cultivation

This section contains historical Plants For A Future notes marked noncommercial.

Succeeds in a well-drained fertile soil in full sun[2][4]. Judging by the plants natural habitat, it should also succeed in poor acid soils and dry soils[K]. The young growth in spring can be damaged by late frosts. Plants have brittle branches and these can be broken off in strong winds[4]. Plants are also susceptible to coral spot fungus[2]. Plants in this genus are notably resistant to honey fungus[4]. This species is a small suckering shrub, it can spread freely in suitable conditions[K]. There is some confusion over the correct name of this species. It is united with R. radicans (under that name) by some botanists whilst others split this species off into another genus, Toxicodendron, and unite it with R. radicans as Toxicodendron radicans[4]. 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[1][8]. The toxic species are sometimes separated into their own genus, Toxicodendron, by some botanists[4]. Dioecious. Male and female plants must be grown if seed is required.

References

  1. F. Chittendon. RHS Dictionary of Plants plus Supplement. 1956 Oxford University Press 1951-00-00

    ↩

  2. Bean. W. Trees and Shrubs Hardy in Great Britain. Vol 1 - 4 and Supplement. Murray 1981-00-00

    ↩1↩2↩3↩4↩5

  3. Buchanan. R. A Weavers Garden.

    ↩

  4. Huxley. A. The New RHS Dictionary of Gardening. 1992. MacMillan Press 1992-00-00 ISBN 0-333-47494-5

    ↩1↩2↩3↩4↩5↩6↩7↩8↩9↩10↩11

  5. Weiner. M. A. Earth Medicine, Earth Food. Ballantine Books 1980-00-00 ISBN 0-449-90589-6

    ↩1↩2

  6. Castro. M. The Complete Homeopathy Handbook. Macmillan. London. 1990-00-00 ISBN 0-333-55581-3

    ↩1↩2↩3

  7. Moerman. D. Native American Ethnobotany Timber Press. Oregon. 1998-00-00 ISBN 0-88192-453-9

    ↩1↩2

  8. Grieve. A Modern Herbal. Penguin 1984-00-00 ISBN 0-14-046-440-9

    ↩1↩2↩3↩4↩5↩6↩7↩8

  9. Fernald. M. L. Gray's Manual of Botany. American Book Co. 1950-00-00

    ↩

  10. Sheat. W. G. Propagation of Trees, Shrubs and Conifers. MacMillan and Co 1948-00-00

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