Weed Identification

Australia > > Prickly Pear (common)

Prickly Pear (common)

Opuntia stricta

THIS PLANT HAS BEEN DECLARED A WEED OF NATIONAL SIGNIFICANCE

Alternative Name(s): Erect Prickly Pear.

Family: Cactaceae.

Form: Shrub

Origin: Native to the Caribbean region.

Flowers/Seedhead: Flowers: yellow, mostly on the margins of the fleshy segments. Flowers late spring to summer.

Description: An erect shrub to 1 m (rarely to 2 m) high. True leaves are shed early and stem segments are often incorrectly referred to as leaves. Lower segments may be thickened and trunk-forming on older plants while flattened upper segments are up to 40 cm long and up to 25 cm wide. Fruit are egg-shaped with a depressed top, purple when ripe and edible. Seeds pale brown, to 5 mm long.

Distinguishing features: Distinguished by showy yellow flowers about 6 cm wide; presence of small bristles (glochids) in clusters in depressions (areoles) on segments and fruit, these glochids readily attach to skin and are difficult to remove; areoles on segments may also have 1 or no spines to 6 cm long.

Dispersal: Spread by seed or vegetatively by segments that root where they contact the ground.

Confused With: Other Opuntia species but none of the naturalised ones look like the pictures shown here.


Yellow flowers are borne on succulent
segments, Tamworth, NSW, Nov
photo J.R. Hosking

Notes: Common Prickly Pear was the major weed problem in large areas of northern NSW and central Queensland in the early 1900s. This cactus is now found over a larger area but is rarely a problem. During the 1920s and 1930s various biological control agents were released for its control. Two of these, Cactoblastis Cactoblastis cactorum (see photo) and a cochineal, Dactylopius opuntiae, control this cactus in most areas.

References:

    Noxious Weeds of Australia. W. Parsons and E. Cuthbertson, 1992, pages 364366. Plant Protection Quarterly. J. Hosking et al., 1988, Vol. 3, pages 115123.

Web References: Search Australian web sites for further information on this weed.


Larvae of Cactoblastis cactorum

Fruit forms at base
of the flower

This weed has been included in the WEEDeck field guide as card S12.
More information about WEEDeck is available from Sainty & Associates Pty. Ltd.

It has also been included in the 'Jumping the Garden Fence' report (WWF-Australia PDF - 1.19mb) which examines the impact of invasive garden plants on Australian agricultural land and natural ecosystems.

 

Australia > > Prickly Pear (common)

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