Poison Ivy
Rhus radicans

Family: Anacardiaceae

What it is like

Rhus radicans is a deciduous Climber growing to 2.5 m (8ft 2in) at a fast rate. See above for USDA hardiness. It is hardy to UK zone 5 and is not frost tender. It is in flower from May to June, 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 soil.

Height (m): 2.5

Where it is found

Woods, on rocky slopes and in wooded swamps.

Eastern N. America - Quebec to Florida, west to Texas..

Conservation Status:

Countries/locations it is found in

How it is used

Food

Rating: 0

Oil: Oil

Medicine

Rating: 1

Poison ivy 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. This plant has been used in the past by physicians in the treatment of paralysis and liver disorders. A decoction of the leaves has been used as a tonic and rejuvenator. The whole or the broken leaves have been rubbed over the skin to treat boils and skin eruptions. The leaves have been rubbed on skin that has been affected by a poison ivy reaction.

Hepatic: Acts on the liver (for better or worse!).

Skin: Plants used in miscellaneous treatments for the skin.

Tonic: Improves general health. Slower acting than a stimulant, it brings steady improvement.

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 excellent marking ink is obtained from this plant.

Dye: Plants that provide dyes.

Ink: Plants that can be used as an ink.

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.

How it is grown

Succeeds in a well-drained fertile soil in full sun. The young growth in spring can be damaged by late frosts. A fast-growing but short-lived species in the wild. It has 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. The plant has a semi-climbing habit and produces aerial roots, and occasionally reaches the size of a small tree. 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;

Habit: Climber

Hardiness: 4-8

Growth: Fast

Soil: Light (sandy), medium, heavy (clay)

Shade: No shade

Moisture: Moist

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. toxicodendron. non L. Toxicodendron radicans. (L.)Kuntze. T. vulgare.