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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Rhus (Toxicodendron succedaneum) is a small to medium-sized deciduous tree growing 2-5 metre tall, sometimes reaching 8-10 metres in favourable conditions, and as wide. Leaves have brightly coloured autumn foliage. The trunk is grey with vertical old lenticel marks, the branchlets (branches) also have lenticels ( a loosely packed mass of cells in the bark of a woody plant used for gas exchange), and are hairless. The bright green leaves are alternate and consist of 9-15 leaflets, also ways with a terminal leaflet (a single leaflet at the apex of leaf), which change to scarlet and crimson in autumn. The lance to egg shaped leaflets are opposite and range between 5-10 cm long and 2-3 cm wide. The leaflet margins are smooth and both surfaces are hairless. The lower surface can be somewhat greyish. The overall length of the leaf ranges from 10-30 cm long. The leaf stalk ranges from 3-10 cm long.
Flowers are creamy-white to yellowish-green and are clustered into branched flowering heads (panicles) which are 8-15 cm long and hairless.
Fruits are pale brown round to egg shaped and compressed laterally, 6-10 mm long, 7-11 mm wide, with a hard stone in the centre (Parsons & Cuthbertson 2001).
For further information and assistance with identification of Rhus contact the herbarium in your state or territory
Yellow, White or Green
Rhus (Toxicodendron succedaneum) grows mainly in temperate regions on a wide range of soils. It is found along roadsides, waste place and is usually found in disturbed areas in woodland. It is a common garden plant in southern Australia that sometimes spreads in to urban woodland (Parsons & Cuthbertson 2001).
The introduced Chinese Pistachio (Pistacia chinensis) is a similar tree but is distinguished from Rhus by having leaves which mostly lack a single terminal leaflet. The leaf underside of Chinese Pistachio is not greyish.
The native species Scentless Rosewood (Synoum glandulosum) and Ribbonwood (Euroschinus falcatus) have similar leaves and berry-like fruits. However, they do not change colour in autumn or lose their leaves in winter.
Native Red Cedar (Toona ciliata) is deciduous and has compound leaves, but they usually have no terminal leaflet (except occasionally in young growth) and the leaf is larger (15-45cm long) with 8-20 leaflets.
White Cedar (Melia azedarach) is a native tree which also retains its fruits on the tree through winter. The fruits are larger than those of Rhus (up to 2cm diameter) and are cream coloured. However, the leaves of white cedar are bipinnate, that is, at least some of the leaflets are themselves further divided into leaflets. The flowers are mauve, not creamy-white to yellowish-green, and produced in large showy clusters.
tree of heaven (Ailanthus altissima) has leaves with 5-20 pairs of leaflets and a single terminal leaflet (i.e. the leaves are imparipinnate). Its leaves turn yellow in colour before they are shed and its large (3-5 cm long) winged fruit (i.e. samara) turn reddish then eventually pale brown as they mature (DEEDI 2020).
Rhus (Toxicodendron succedaneum) sap causes severe dermatitis in humans and all parts of the plant are toxic (Parson & Cuthbertson 2001), and can invade some habitats in temperate and sub-tropical regions.
Native ecosystems: A potential weed of disturbed sites, including forests, open woodlands, and urban bushland.
Urban areas: Also a weed of roadsides, gardens and waste areas.
Human impacts: Severe painful allergic reactions can occur between 12 hours and 7 days after contact. These reactions include severe dermatitis that begins with a rash, redness, itching and blisters where skin has made contact with the tree. Localised swelling of the face, arms and legs is often associated with the rash. All of these symptoms usually last 7 to 10 days. However, chronic sufferers or more sensitive individuals may experience more extreme symptoms over a longer period of time. Contact with any part of the tree can cause these symptoms, but it is the sap that can cause the most severe reaction. Sensitivity to this plant can have an accumulative effect over a number of years, with initial exposure not necessarily causing a significant reaction. However, subsequent contact will result in stronger allergic reactions. Warning: For all eye exposures to sap, rinse the eye with water for 15 minutes and then seek urgent medical assistance (Queensland Government 2020).
Rhus (Toxicodendron succedaneum) mostly reproduces by seeds and occasional locally vegetatively via suckers Brisbane City Council (2020). Dispersal of Rhus by seed has principally been through commercial nurseries and subsequently via birds and other animals (Parson & Cuthbertson 2001). Rhus can be spread by movement of garden soil containing seed and, as seed remains viable for many years, care should be taken when using soil previously associated with a rhus tree (Monaghan & McMaugh 2002).
The introduction of Rhus into Australia is unknown. However, it is commonly cultivated in southern Australia especially around Sydney and Melbourne (Parson & Cuthbertson 2001).
Rhus (Toxicodendron succedaneum) management generally relates to either the removal of single ornamental trees, or the control of small outbreaks of seedlings or young trees in bushland areas. Mechanical removal of Rhus is the main method of control (Parson & Cuthbertson 2001). Care must be taken in all Rhus control situations as any contact with the tree is dangerous. Physical removal of trees has high associated risks of poisoning, and difficulties of disposing of the plant material. Wear protective clothing at all times. However a safe method of control is probably by stem injection of herbicide (see Chemical control below).
Chemical control: The safest method of control is probably by stem injection of herbicide (DPI, NSW 2019), also known as Cut stump. Other methods include the basal bark treatment and is suitable for trees or shrubs that are actively growing and not stressed. It is not suitable for plants with thick, papery bark, and involves painting the stems with herbicides. for further information see: Brisbane City Council (2020). Please also see the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au
Non-chemical control: Physical control Preferably undertake removal in the winter months when the leaves have been shed to minimise toxicity then grub the trees, making sure most of the root system is removed so as to minimise suckering. Do not burn Rhus as the allergen is especially harmful as an airborne oil (Parson & Cuthbertson 2001).
Rhus (Toxicodendron succedaneum) spreads via seeds and these germinate in spring producing a single erect stem and fibrous roots. Short rhizomes form on the basal portions of the stem towards the end of summer. Seedlings are dormant during winter. Flower buds do not develop until late summer of the second growth season. Flowering does not occur until the following spring when the new season's leaves are fully expanded. Fruit matures in autumn and often remains on the plant over winter (Parsons & Cuthbertson 2001).
Rhus (Toxicodendron succedaneum) is currently only known to occur as a weed in the Central Coast of New South Wales around Sydney (Parson & Cuthbertson 2001); and in and south of Brisbane (AVH 2020).
Rhus is native to Japan, China and the Himalayan region (Parsons & Cuthbertson 2001).
Rhus succedanea L.
Toxicodendron diversilobum auct. non (Torr. & A.Gray) Greene
Rhus Tree, Japanese Tallow Tree, Japanese Wax Tree, Poison Ivy, Scarlet Rhus, Sumac Wax Tree, Red-lac, Wax Tree, Wasboom.