T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network


Opuntia monacantha (Drooping Prickly Pear)

Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Core eudicots
Order: Caryophyllales
Family: Cactaceae
Genus: Opuntia
Species: O. monacantha
Binomial name: Opuntia monacantha
Synonyms: Cactus monacanthus, Platyopuntia brunneogemmia, Platyopuntia vulgaris, Opuntia vulgaris.Common name: Drooping tree pear, Barbary fig, Cochineal Prickly pear, Drooping prickly pear, Drooping tree pear, Smooth tree pear, Spiny prickly pear, Spreading prickly pear, Joseph's Coat, Irish Mittens,

Opuntia monacantha is a cacti native to South America (Brazil to northern Argentina). It is now naturalised in other parts of the world. This plant is regarded as an environmental weed in New Zealand.

O. monacantha is an upright, fleshy, tree like plant that usually grows up to 1.5-3 m tall. O. monacantha often has a definite trunk that is much branched at the top and has drooping, upper branches called cladodes. These cladodes are a flattened organ arising from the stems and replace leaves in photosynthetic function. They are are hairless and have one to three large spines (>10 cm long) on most of the areoles (small raised structures) on their surfaces. These large spines are easily seen on the pads and the stem and fruit of Opuntia monacantha. There are also glochids on the plant and fruit, these are tiny ‘hairs or bristles' that are very hard to see. These have barbed ends and cause irritation on contact with the skin. Once they are lodged in ones skin they are extremely difficult to get out.

The flowers (>6 cm across) that appear from late spring through to early autumn. They are yellow with reddish-coloured markings on their outer petaloids. They are borne singly on fleshy bases along the margins of the stem segments.

The immature green, fleshy, pear-shaped fruit are >7.5 cm long and 2-5 cm wide with depressed tips. They turn a reddish-purple as they mature. The fruits contain small, yellow or pale brown, round, 3-4 mm seeds. The fruits are persistent on the plant.

O. monacantha reproduces by seeds and by stem fragments that become dislodged and develop roots. The stem fragments may become attached to animals, footwear and vehicles. They are also dispersed by flood waters and in dumped garden waste. The fruit are eaten by various fauna and the seeds are then spread in their droppings.

 



The fruit and cladodes.


The flower bud.