Introduced into Australia in the 1920s as a garden ornamental, and first recognised as naturalised in the suburb of Sherwood, Brisbane, leaf cactus is a potential threat to eucalypt communities in subtropical northern Australia. The plant has a tendency to form large impenetrable clumps, and its extreme thorniness makes control of large infestations difficult.
Leaf cactus is native to the West Indies, Venezuela, Guyana, Brazil and Argentina. Elsewhere in the tropics, the plant has either been cultivated or has escaped. It was recorded in 1989 a being localised frequently on north coast of NSW, growing on a river bank amongst native vegetation. Another occurrence in 1993, now removed by a bush regeneration team, was recorded at Bar Island on the central coast of NSW.
The spread of leaf cactus throughout the world has been assisted by its ornamental value and its nutritional properties. Leaf cactus reproduces vegetatively from branch cuttings, leaves and seeds. Its main cause of spread is by birds eating the fruit (often from garden plants) and dropping them under the trees in which they perch. Once it is established in the soil, the plant seeks out the trunk of the tree and gradually climbs up to form dense thickets in the branches and canopy.
Dumping of the plant in roadside vegetation is another likely cause of spread. Where leaf cactus is near creeks and other water bodies, pieces of the plant may be washed downstream a considerable distance to establish new populations. In cities, birds can also move propagules (seeds or other parts from which a plant can reproduce) a long way from gardens using corridors provided by parks, streets, drains and other watercourses.
Leaf cactus is a perennial, spiky, climbing shrub (liana) that attaches itself to trees in a vine-like manner, growing up to 12 m high. It has long, slender spines in groups along the trunk of the plant, and short recurved spikes in pairs on the branches.
It bears unusually shaped small yellow to orange edible fruits 25 to 45 mm in diameter, which are popular with birds. The fruit contains a single black seed up to 5 mm in diameter.
The scented flowers can be white or pale yellow, sometimes ageing to pink, and are approximately 20–55 mm in diameter. There are numerous, long, yellow-tipped orange stamens in the middle of the flower. A prominent white style (the female part of the flower) sits in between the stamens. The flowers are generally grouped together to produce attractive bunches on the plant.
As its name suggests, leaf cactus belongs to a small group of cactus species that have leaves. The leaves are waxy, slightly succulent and edible. They are a flattened egg-shape with pointed ends, and approximately 45–110 mm long by 15–50 mm broad.
It grows quite vigorously in tropical and subtropical environments, and is drought tolerant. Leaf cactus adapts to a wide variety of soil types, but seems to prefer well-drained, high nutrient soils. It dislikes too much water. Its native subtropical climate is warm for most months of the year, but can experience cool winters.
CRC for Australian Weed Management: Rachel McFadyen (Weeds CRC), Jim Space (US Forest Service), Jean Moore (Alien Plant Watch), Willem Hofland (Wildlife and Environment Society of South Africa).
Because there are relatively few leaf cactus infestations, it can still be eradicated. Any new outbreaks should be reported immediately to your local council weed officer. Do not try to control leaf cactus without their expert assistance. Control effort that is poorly performed or not followed up can actually help spread a weed and worsen the problem.
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Regionally Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant