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Scientific Name
Synonyms
Family
Common Names
Origin
Naturalised Distribution
Habitat
Habit
Distinguishing Features
Stems and Leaves
Flowers and Fruit
Reproduction and Dispersal
Environmental Impact
Legislation
Management
Similar Species
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Click on images to enlarge

habit in fruit (Photo: Sheldon Navie)

habit in flower (Photo: Sheldon Navie)

stem segment with spines (Photo: Sheldon Navie)

flower buds and young stem segment with tiny leaves (Photo: Sheldon Navie)

flowers (Photo: Sheldon Navie)

close-up of flower (Photo: Sheldon Navie)

immature fruit (Photo: Sheldon Navie)

mature fruit (Photo: Sheldon Navie)

close-up of mature fruit (Photo: Sheldon Navie)

close-up of seeds (Photo: Carole Ritchie at USDA PLANTS Database)

young plant (Photo: Sheldon Navie)

Opuntia dillenii

Scientific Name

Opuntia dillenii (Ker-Gawl.) Haw.

Synonyms

Cactus dillenii Ker-Gawl.
Opuntia stricta (Haw.) Haw. var. dillenii (Ker-Gawl.) L. Benson

Family

Cactaceae

Common Names

Australian pest pear, common prickly pear, Dillen's prickly pear, Eltham Indian fig, erect prickly pear, Gayndah pear, pipestem prickly pear, prickly pear, sour prickly pear, spiny pest pear, spiny pest-pear, sweet prickly pear, sweet prickly-pear.

Origin

Native to south-eastern USA (i.e. Alabama, Florida, Georgia, South Carolina and Texas), Mexico, Central America, the Caribbean and parts of northern South America (i.e. Ecuador).

Naturalised Distribution

This species is naturalised in the eastern parts of Australia, and once infested very large areas. It has been recorded in southern and central Queensland and in some parts of New South Wales. However, its current distribution may be underestimated because it is easily mistaken for common prickly pear (Opuntia stricta).

Also naturalised in South Africa and on the Galapagos Islands.

Habitat

A weed of semi-arid, sub-tropical, tropical and warmer temperate regions. It may inhabit open woodlands, rangelands, grasslands, pastures, creekbanks, roadsides, railways lines, coastal environs, gardens, disturbed sites and waste areas.

Habit

An upright (i.e. erect) or more often spreading, fleshy (i.e. succulent), plant usually growing 50-100 cm tall, but occasionally reaching up to 2 m in height.

Distinguishing Features

Stems and Leaves

The stems are much-branched and consist of a series of flattened fleshy (i.e. succulent) segments, which are sometimes confused for leaves. These segments (10-40 cm long, 5-20 cm wide and 1-2 cm thick) are green or bluish-green in colour and longer than they are broad (i.e. elliptic or obovate in shape). They are hairless (i.e. glabrous) and covered in small raised bumps (i.e. areoles) which bear tiny spiny bristles (i.e. glochids). Most of these small raised bumps (i.e. areoles) also have 1-7 larger sharp spines (2-4 cm long).

The leaves are reduced to small, slightly curved, cone-shaped (i.e. conical) structures (up to 6 mm long) and are quickly shed (i.e. they are caducous).

Flowers and Fruit

The flowers (up to 7 cm long and 6-8 cm across) are bright yellow and sometimes have greenish or pinkish coloured markings on the outer 'petals'. They are borne singly on fleshy bases and are mostly found along the margins of the stem segments. These flowers have numerous 'petals' (most of these are actually petal-like structures known as petaloids), 25-50 mm long, and numerous stamens. Flowering occurs mostly during spring and summer.

The immature fruit are green, but they turn reddish-purple in colour as they mature. These fruit (4-9 cm long and 3-4 cm wide) are fleshy (i.e. succulent), pear-shaped (i.e. pyriform) or almost rounded (i.e. globose), berries. They may have a shallow depression at the top, especially when they are young, and always have several tufts of small barbed bristles (i.e. glochids) on their surface. The reddish or purplish coloured pulp in the centre of the fruit contains large numbers of seeds. These seeds (4-5 mm long and 4-4.5 mm wide) are generally yellow or pale brown in colour and somewhat rounded (i.e. sub-globose) in shape.

Reproduction and Dispersal

This plant reproduces by seed and also vegetatively via its fleshy (i.e. succulent) stem fragments (i.e. the stem segments may become dislodged and develop into new plants).

Stem fragments are spread by becoming attached to animals, footwear and vehicles. They are also dispersed in floodwaters and dumped garden waste. The fruit are eaten by various animals (e.g. birds and foxes) and the seeds then spread in their droppings.

Environmental Impact

Spiny pest pear (Opuntia dillenii) is regarded as an environmental weed in Queensland and New South Wales. It is also listed in the Global Invasive Species Database, and is regarded to be in the top 100 of the world’s worst invasive alien species.

Legislation

This species is declared under legislation in the following states and territories:

Management

For information on the management of this species see the following resources:

Similar Species

Spiny pest pear (Opuntia dillenii) is very similar to common prickly pear (Opuntia stricta) and intermediates between the two species are sometimes seen in Australia. It is also similar to Indian fig (Opuntia ficus-indica), white-spined prickly pear (Opuntia streptacantha), drooping tree pear (Opuntia monacantha) and velvety tree pear (Opuntia tomentosa). These species can be distinguished by the following differences: