We need regular donations to enable us to keep going – to maintain and further develop our free-to-use database of over 8000 edible and useful plants. Donations have increased following recent appeals - thank you! - but we still need at least £1000 (or $1300/ €1200) every month. If you value what we do please give what you can to support our work. More >>>

Follow Us:

 

Rhus diversiloba - Torr.&A.Gray.

Common Name Western Poison Oak, Pacific poison oak
Family Anacardiaceae
USDA hardiness 4-8
Known Hazards All parts of the plant 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 can cause problems[274].
Habitats Thickets and wooded slopes in foothills, along streams, in washes and hedgerows below 1500 metres[71, 92].
Range Western N. America - Vancouver to California.
Edibility Rating    (0 of 5)
Other Uses    (2 of 5)
Weed Potential No
Medicinal Rating    (2 of 5)
Care (info)
Fully Hardy Moist Soil Full sun
Rhus diversiloba Western Poison Oak, Pacific poison oak


Rhus diversiloba Western Poison Oak, Pacific poison oak

 

Translate this page:

Summary


Physical Characteristics

 icon of manicon of shrub
Rhus diversiloba is a deciduous Shrub growing to 2.5 m (8ft 2in).
See above for USDA hardiness. It is hardy to UK zone 5 and is not frost tender. 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, prefers well-drained soil and can grow in nutritionally poor soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It cannot grow in the shade. It prefers moist soil.

UK Hardiness Map US Hardiness Map

Synonyms

Toxicodendron diversilobum. (Torr.&Gray.)Greene.

Habitats

Woodland Garden Sunny Edge;

Edible Uses

Edible Parts: Oil
Edible Uses: Oil

None known

References   More on Edible Uses

Medicinal Uses

Plants For A Future can not take any responsibility for any adverse effects from the use of plants. Always seek advice from a professional before using a plant medicinally.
Antidote  Contraceptive  Eczema  Ophthalmic  Warts

Western poison oak was employed medicinally by some native North American Indian tribes who used it to treat various complaints[257]. In view of the potential toxicity of the plant, extreme caution is advised in any use of it. See the notes above on toxicity. A leaf has been swallowed in the spring as a contraceptive[257]. A tincture of the fresh leaves has been used in the treatment of eczema and skin diseases[4]. It is also used in the treatment of warts, ringworm etc[92]. A poultice of the fresh leaves has been applied to rattlesnake bites[257]. The leaf buds have been eaten in the spring in order to obtain immunity from the plant poisons[257] A moxa of the plant has been used in the treatment of warts and ringworm[257]. The juice of the plant has been used as a treatment for warts[257]. An infusion of the dried roots has been taken in order to give immunity against any further poisoning[257]. A decoction of the roots has been used as drops in the eyes to heal tiny sores inside the eyelids and to improve vision[257].

References   More on Medicinal Uses

Now available: PLANTS FOR YOUR FOOD FOREST: 500 Plants for Temperate Food Forests and Permaculture Gardens.

An important new book from PFAF. It focuses on the attributes of plants suitable for food forests, what each can contribute to a food forest ecosystem, including carbon sequestration, and the kinds of foods they yield. The book suggests that community and small-scale food forests can provide a real alternative to intensive industrialised agriculture, and help to combat the many inter-related environmental crises that threaten the very future of life on Earth.

Read More

FOOD FOREST PLANTS

Other Uses

Basketry  Dye  Ink  Mordant  Oil

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[169]. An oil is extracted from the seeds[4]. It attains a tallow-like consistency on standing and is used to make candles. These burn brilliantly, though they emit a pungent smoke[4]. The supple stems are used as the warp in basket making[92]. Slender stems are used as circular withes in basket making[257]. An excellent black dye is obtained by exposing the sap to air[92].

Special Uses

References   More on Other Uses

Cultivation details

Succeeds in a well-drained fertile soil in full sun[200]. Plants do not require a rich soil[11]. The young growth in spring can be damaged by late frosts. Plants have brittle branches and these can be broken off in strong winds[200]. Plants are also susceptible to coral spot fungus[11]. This species is closely related to R. toxicodendron[1]. 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, 4]. The toxic species are sometimes separated into their own genus, Toxicodendron, by some botanists[200]. Plants in this genus are notably resistant to honey fungus[200]. Dioecious. Male and female plants must be grown if seed is required.

References   Carbon Farming Information and Carbon Sequestration Information

Temperature Converter

Type a value in the Celsius field to convert the value to Fahrenheit:

Fahrenheit:

image

The PFAF Bookshop

Plants For A Future have a number of books available in paperback and digital form. Book titles include Edible Plants, Edible Perennials, Edible Trees, and Woodland Gardening. Our new book to be released soon is Edible Shrubs.

Shop Now

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[200]. The stored seed also needs hot water treatment and can be sown in early spring in a cold frame[200]. 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[200]. Root cuttings 4cm long taken in December and potted up vertically in a greenhouse. Good percentage[78, 200]. Suckers in late autumn to winter[200].

Other Names

If available other names are mentioned here

Found In

Countries where the plant has been found are listed here if the information is available

Weed Potential

Right plant wrong place. We are currently updating this section. Please note that a plant may be invasive in one area but may not in your area so it’s worth checking.

Conservation Status

IUCN Red List of Threatened Plants Status :

Related Plants
Latin NameCommon NameHabitHeightHardinessGrowthSoilShadeMoistureEdibleMedicinalOther
Rhus ambigua Climber0.0 6-9  LMHSNM002
Rhus aromaticaLemon Sumach, Fragrant sumacShrub1.2 3-9 SLMHNDM422
Rhus chinensisChinese Gall, Chinese sumacTree6.0 7-10  LMHNM232
Rhus copallinaDwarf Sumach, Winged sumac, Flameleaf Sumac, Winged Sumac, Shining SumacShrub2.0 4-10 FLMHNDM423
Rhus coriariaElm-Leaved Sumach, Sicilian sumacShrub3.0 8-11  LMHNDM212
Rhus glabraSmooth SumachShrub3.0 3-9 MLMHNDM433
Rhus integrifoliaLemonade Berry, Lemonade sumacShrub2.0 8-10 MLMHNDM202
Rhus microphyllaDesert Sumach, Littleleaf sumacShrub2.0 8-11  LMHND202
Rhus ovataSugar Bush, Sugar sumacShrub2.0 8-11  LMNDM212
Rhus potaninii Tree12.0 4-8  LMHNM022
Rhus punjabensis Tree12.0 5-9  LMHNM322
Rhus punjabensis sinica Tree12.0 5-9  LMHNM322
Rhus radicansPoison IvyClimber2.5 4-8 FLMHNM012
Rhus sempervirens Shrub3.5 -  LMHNDM212
Rhus succedaneaWax TreeTree9.0 4-9  LMHNM124
Rhus sylvestris Tree10.0 -  LMHNM002
Rhus toxicodendronEastern Poison OakShrub0.6 6-9  LMHNDM022
Rhus trichocarpa Tree6.0 -  LMHNM002
Rhus trilobataSkunk Bush, Basketbush, Squawbush, Three Leaf SumacShrub1.8 4-6 MLMHNDM423
Rhus typhinaStag's Horn Sumach, Velvet Sumac, Staghorn SumacShrub6.0 4-8 FLMHNDM423
Rhus vernixPoison SumachShrub3.0 3-7  LMHNMWe012
Rhus wallichii Tree8.0 -  LMHNM012
Rhus x pulvinata Shrub3.0 0-0  LMHNDM422

Growth: S = slow M = medium F = fast. Soil: L = light (sandy) M = medium H = heavy (clay). pH: A = acid N = neutral B = basic (alkaline). Shade: F = full shade S = semi-shade N = no shade. Moisture: D = dry M = Moist We = wet Wa = water.

 

Print Friendly and PDF

Expert comment

Author

Torr.&A.Gray.

Botanical References

1171200

Links / References

For a list of references used on this page please go here

Readers comment

M Benton   Thu Jul 30 2009

I was really curious as to why propagation instructions were given for poison oak in the Plants for the Future database. Even greenhouse instructions were given. The plant is so toxic that it almost melts my family's skin and guarantees misery for weeks. Why tell people how to grow MORE of it?

Add a comment

If you have important information about this plant that may help other users please add a comment or link below. Only comments or links that are felt to be directly relevant to a plant will be included. If you think a comment/link or information contained on this page is inaccurate or misleading we would welcome your feedback at admin@pfaf.org. If you have questions about a plant please use the Forum on this website as we do not have the resources to answer questions ourselves.

* Please note: the comments by website users are not necessarily those held by PFAF and may give misleading or inaccurate information.

To leave a comment please Register or login here All comments need to be approved so will not appear immediately.

Subject : Rhus diversiloba  
© 2010, Plants For A Future. Plants For A Future is a charitable company limited by guarantee, registered in England and Wales. Charity No. 1057719, Company No. 3204567.