Quick Facts

Quick facts

• Drooping Prickly Pear (Opuntia monacantha) is not as invasive as common Prickly Pear (Opuntia stricta) and largely favours moister regions.
• Stem segments fragment and can be distributed by animals, vehicles or water.
• Fruits are succulent and are eaten by birds and animals and seed is distributed in their droppings.
• It can cause injury to people and animals.
• It is not considered a major weed in any state but if this species is seen please notify your local weed management authority.

What Does It Look Like?

What is it?

Drooping Prickly Pear (Opuntia monacantha) is a tall shrub or small tree 2–7 m tall often with drooping branches. The trunk is often well-developed, to 25 cm in diameter, with prominent clusters of large spines to 10 cm long. The thin (4–6 mm thick) stem-segments are mid to dark green, shiny or glossy, egg-shaped and often elongated, 10–45 cm long and 6–15 cm wide. The areoles (spots on stem segments and fruits that contain the spines and glochids) are scattered and woolly with clusters of small brown glochids (clusters of small barbed bristles). There are 1–2 spines per areole, each spine 2.5–5 cm long. The leaves are very small and drop off.

The flowers are 3–7 cm diameter. The petaloid lobes are yellow but the outer smaller ones are often reddish or streaked red.

The red-purple fruits are pear-shaped, 5–7.5 cm long, 2–3 cm broad and taper into a stalk-like base (Telford 1984; Swinbourne 1986; Harden 1990; Stajsic & Carr 1996; Anderson 2001; Chinnock 2007, pers. comm.).

For further information and assistance with identification of Drooping Prickly Pear contact the herbarium in your state or territory.

Flower colour

Yellow

Growth form (weed type/habit)

Tree, Shrub

Where it currently grows? Preferred habitat

Drooping Prickly Pear is mostly found in sub-tropical, semi-arid and warmer temperate environments. It is a weed of pastures, open woodlands, waterways, roadsides, railways and coastal areas often on sand. It tolerates shaded areas and higher rainfall compared to many other Prickly Pears (Navie 2004; Chinnock 2007 pers. comm.).

Are there similar species?

Drooping Prickly Pear is a distinctive Prickly Pear and is not likely to be confused with other species. It is a relatively tall shrub or small tree and forms a well-developed trunk with clusters of long spines. Stem segments are thin, mid to dark green, smooth, shiny or glossy and the upper branch stem segments usually droop especially when in fruit. The fruits often develop in chains. They are long and tapering towards the base (Navie 2004, Chinnock pers. comm. 2007).

Common Prickly Pear (Opuntia stricta) differs in being a low growing shrub with thicker, very pale green or grey green stem segments which either lacks spines or has 1–11 spines and fruits with very prominent scattered areoles with obvious clusters of glochids (Navie 2004, Chinnock pers. comm. 2007).

Wheel Cactus (Opuntia robusta) differs in having very large round stem segments (to 45 cm diameter) that are very bluish (Navie 2004, Chinnock pers. comm. 2007)

Riverina Pear (Opuntia elata) forms a shrub to 3 metres. The stem segments are smooth, shiny, greater than 10 mm thick, deep green but usually reddish to reddish brown on the margins and around the areoles. Flowers are orange yellow (Navie 2004, Chinnock pers. comm. 2007).

Indian Fig (Opuntia ficus-indica) forms a shrub or small tree 1–5.5 m tall. The stem segments are obovate to broadly obovate and very thick 2–3 cm thick, mid green. The yellow flowers are solitary, 7–10 cm diameter (Navie 2004, Chinnock pers. comm. 2007).

Why Is It A Weed?

What are its impacts?

The impacts of Drooping Prickly Pear are similar to those of Tiger Pear (Opuntia aurantiaca).

Agriculture: It is a drought tolerant weed and can form dense infestations which impede movement of stock and people and lay waste to agricultural and pastoral lands. The infestations could provide protection for feral animals.

Human impacts: The spines and glochids can cause injury to humans and animals (Parsons & Cuthbertson 2001; DPI 2007).

Native ecosystems: Dense infestations can affect biodiversity by hindering growth and regeneration of native plants (Muyt 2001).

How does it spread?

Drooping Prickly Pear readily reproduces from stem fragments and immature fruits, which easily break off and root, or from seed. The succulent fruits are attractive to birds and animals and the seeds are carried in their droppings. Plants growing adjacent to creeks and waterways can be dispersed readily downstream and much further during floods. Discarded plants can lead to new outbreaks (Navie 2004; Chinnock pers. comm. 2007)

What is its history in Australia?

The first introduction of Drooping Prickly Pear is thought to have been by Governor Phillip at Port Jackson in 1788 along with Common Prickly Pear and possibly a couple of other species with the intention of developing a cochineal industry for the new colony. It is unknown whether these original plants survived. Drooping Prickly Pear appeared regularly in nursery catalogues throughout Australia in the 1840s (Parsons & Cuthbertson 2001).

How To Manage It?

Best practice management

Non-chemical control: Physical removal of plants and burning is very effective but the fire must be intense to ensure destruction of all parts of the plant. 

Chemical control: A number of herbicides are also effective by spraying or injecting (Parsons & Cuthbertson 2001).

Please see the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au

Biological control: Drooping Prickly Pear has also been recognised as a target for biological control through a cross-jurisdictional government process. This allows activities to be undertaken to develop effective biological controls. Biological control by Monacantha Cochineal Insect (Dactylopius ceylonicus) can be used in suitable areas. Cochineal can be transferred manually by placing a few affected stem segments on unaffected plants. In areas where the insect does not kill plants it may have helped restrict the spread of the species (Parsons & Cuthbertson 2001).

Does it have a biological control agent?

YES

When does it grow? (lifecycle/growth calendar)

Drooping Prickly Pear is most active in warmer months from spring and autumn. Flowering occurs from October onwards but peaks during summer. Seeds germinate at any time of the year. Plants often grow erect 1–1.5 m developing a strong central stem system before laterally branching occurs (Chinnock 2007, pers. comm.; DPI 2007)

Where Is It Found?

Which states and territories is it found?

NSW, NT, QLD, SA, VIC, WA

What areas within states and territories is it found?

Drooping Prickly Pear is a very widespread and relatively common in northern Queensland and south-eastern South Australia. It also has a scattered distribution in largely coastal south-eastern Queensland, eastern New South Wales, Victoria, South Australia and south-western Western Australia (Navie 2004).

Where does it originate?

Drooping Prickly Pear is widely distributed throughout Brazil, Paraguay, Uruguay and Argentina (Anderson 2001).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

YES

Where is it a declared weed?

In all states and territories.

Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?

NO

Government weed strategies and lists – Weeds Australia

Is it on the Agricultural Sleeper List?

NO

Government weed strategies and lists – Weeds Australia

Names And Taxonomy

Main scientific name

Opuntia monacantha

Other scientific names (synonyms)?

• Cactus monacanthos Willd.
• Opuntia vulgaris Mill. (misapplied by Harden, G.J. 1990, Cactaceae. Flora of New South Wales. 1: 203.; Stajsic, J. & Carr, C.W. 1996, Cactaceae. Flora of Victoria. 3: 125-126, Fig. 25w-y.)

Does it have other known common name(s)?

Drooping Tree Pear, Smooth Tree Pear, Barbary