APC (2020). The Australian Plant Census, Council of Heads of Australasian Herbaria, Available at: https://biodiversity.org.au/nsl/services/apc . [accessed 7/12/2020].
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Poison Ivy (Toxicodendron radicans) is a a winter deciduous plant, typically occurring as woody vine to 15 metres tall or a shrub to 1.2 metre, often with aerial roots. Young shoots are densely hairy and greenish. The leaves occur alternately along the stem and consist of three (rarely five) leaflets. Leaf stalks are densely hairy, with the two lateral leaflet stalks shorter than the longer terminal leaflet stalk. The egg shaped leaflets are occasionally deeply lobed, to having course or no teeth along the margins (along its edge), and the leaf margin and surface is normally smooth, rarely hairy. The overall length of the leaf ranges from 70 to 400 mm, with individual leaflets 30–120 mm or rarely up to 300 mm. The leaves are green in spring and summer and change to yellow, orange-red or crimson in the autumn, before falling. Robust areal roots grow from stems nodes of the the vine-like stems in some plants (Parsons & Cuthbertson 2001).
Individual plants are either male or female, that is, the male and female flowers occur on separate plants.
Flowers are small 2-5 mm in diameter, yellowish green, have 5 petals, and are clustered into panicles (loosely branching flowering stalks) up to 100 mm long.
Fruits are roundish, creamy white to brown, and up to 4 mm in diameter. They contain a greyish striped seed (Parsons & Cuthbertson 2001; Tenaglia 2007).
For further information and assistance with identification of Poison Ivy contact the herbarium in your state or territory.
Yellow or yellow-green
Vine or shrub
In Australia Poison Ivy (Toxicodendron radicans) grows in gardens. Around the world where Poison Ivy grows wild, it is mainly found within the temperate regions on regularly disturbed sandy or stony soils in fields, pastures, thickets, and waste places.
There are no known similar species in Australia.
Human impacts: Poison Ivy (Toxicodendron radicans) sap causes severe dermatitis in humans, while most animals including cattle, horses, sheep, goats, pigs and birds are immune (Parson & Cuthbertson 2001). The sap is contained within all parts of the plant especially in the leaves and bark of the stems and trunk, and is released only when the plant is bruised or broken casing irritation to people. The toxic effect can also occur when contact of sap is made via other articles, such as clothes, tools, and animals. Sap can remain active for more than a year in dry conditions but can be removed by washing (Parsons & Cuthbertson 2001).
If contact occurs with Poison Ivy and if:
Dispersal of Poison Ivy (Toxicodendron radicans) is principally by seed which is readily eaten by birds and other animals. As plants are either male or female, both sexes are needed for seed production. However, once established colonies can increase in size vegetatively by the production of suckers (Parson & Cuthbertson 2001).
The introduction of Poison Ivy (Toxicodendron radicans) into Australia is unknown. However, it is sometimes cultivated as a garden ornamental (Parson & Cuthbertson 2001).
Due to toxicity in the leaves and stem of Poison Ivy (Toxicodendron radicans), preferably undertake removal in the winter months when the leaves have been shed to minimise toxicity.
Chemical control: Where non-chemical control methods are impractical, chemical control can be used when other vegetation is unlikely to be damaged.
Please see the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au
Non-chemical control: Physical control: Physical removal of Poison Ivy is the preferred method. Wear protective clothing at all times. Grubbing is better for small patches Grubbing is the digging out of the plant, or the chopping of the stem of the plant below the ground, using a mattock or chip hoe. Mechanical control: Grubbing using machinery can also be carried out for large infestations. Cultivation or slashing: Repeated cultivation is also effective at controlling P.
Disposal: Do not burn Poison Ivy as the allergen is especially harmful as an airborne oil (Parson & Cuthbertson 2001).
Poison Ivy (Toxicodendron radicans) seeds germinate in spring. Seedlings grow slowly until the first winter and then the roots become dormant. Flower buds do not develop until the second or third growth season in late summer or early autumn. Flowering does not occur until the following spring when the new season's leaves are fully expanded. Fruit matures in late summer and often remains on the plant over winter. The seeds are viable for at least 6 years (Parsons & Cuthbertson 2001).
Poison Ivy (Toxicodendron radicans) has only been known to occur spontaneously as doubtfully naturalised as a possible weed in Queensland (APC 2020). It is occasionally found planted in gardens and has been collected as cultivated specimens from Queensland, South Australia and Tasmania.
Poison Ivy (Toxicodendron radicans) is found in gardens in cool temperate regions, but It is possible that is occurs as cultivated plant throughout Australia, especially in cool temperate to sub humid regions. It rarely occurs spontaneously outside of cultivation in Australia (Parson & Cuthbertson 2001), however, no wild collections of Poison Ivy have been made in Australia to confirm it does occur spontaneously outside of cultivation (AVH 2020).
Poison Ivy is native to North America, from Southern Canada, the United States, British Columbia, Mexico and the Caribbean (Parson & Cuthbertson 2001).
Rhus radicans L.
Poison Ivy, Poison Oak, Climbing Poison Ivy