Opuntia aurantiaca Lindley
Synonyms - Opuntia inermis
Opuntia is Latin of unknown relevance but may refer to the town of Opus.
Aurantiaca is Latin meaning scarlet-orange.
Tiger Pear probably refers to low creeping habit like a tiger and the pear shaped fruit.
Other names:Jointed cactus
Kaatje (South Africa)
Lidjiesturksvy (South Africa)
Summary:Succulent shrub. The segments are cylindrical and elongated, about 30 mm in diameter by up to 100 mm long. The plant is much branched. The spines are carried in clusters of three to seven and are up to 30 mm long. The flower is yellow and the fruit is red and mottled with purple when ripe.
Two, however it doesn't set viable seed so they are not seen.
Leaves:Several tiny, scale like, conical, purplish or pink, scattered, easily detached leaves on the stem surface and apparently below the areoles which are a small circular cushion in the axil of each leaf.
Stems:Erect to almost prostrate, dark green with purplish edges, usually less than 300 mm tall but may grow up to 2000 mm high when supported, fleshy, very spiny, superimposed leaf like joints or segments that are easily broken. Segments rounded, 20-500 mm long x 10-50 mm diameter. Small round cushions or 'eyes' (areoles) scattered across the leaf surface. From the areoles arise many woolly, jointed hairs, tufts of short, fine, pale yellow bristles with tiny bent back barbs and 3-7 brownish, barbed spines up to 40 mm long. The areoles are arranged diagonally around the segments.
Flower head:Flowers on the edges of the joint. Rarely on the face of the joint.
Flowers: Yellow with a fleshy base.
Ovary - 1 style with several stigmas.
Sepals - Many, yellow and greenish on the back.
Petals - Many, overlapping, yellow and greenish on the back. 60-70 mm wide when fully open. More correctly termed petaloids.
Stamens - Many.
Anthers - Many.
Fruit:Egg to pear shaped, spiny berry that turns red and mottled with purple when ripe, 25 mm long x 25 mm thick, circular depression at the top, filled with pink pulp and many seeds.
Seeds:Many but none are viable.
Roots:Short fibrous roots and underground bulbs or tubers. Tubers formed when stem fragments are buried.
Key Characters:Cylindrical phylloclades (stem segments) with areoles with 3-7 spines in diagonal rows.
Red fruit with purple mottles and pink flesh when ripe.
Perennial. This species sets no viable seed. The segments break off readily to form new plants. Roots form from the areoles that are in contact with the ground and new stems form from upper areoles. Segments that are buried form tubers. New plants are produced entirely vegetatively and grow new stems, which again are broken by wind, animals, flood waters or vehicles. Mother plants can live for many years.
Crassulacean acid metabolism (CAM) plant helps preserve water.
Detached stem segments can remain viable indoors for 3 years.
Reproduction:Mainly by stem segments and rarely seed.
Flowering times:Spring to summer in western NSW.
Seed Biology and Germination:No viable seed.
Vegetative Propagules:Stem fragments.
Hybrids:This species is thought to be a sterile hybrid.
Allelopathy:Population Dynamics and Dispersal:
Spread by spiny stem segments attaching to animals and vehicles or floating off in water. Stems are broken easily by animals, wind or flood waters. Local spread is by fruit or stem fragments dropping close to the mother plant and taking root. Long distance dispersal by people transplanting it or disposing it at rubbish dumps and in the bush is still a major form of spread.
Origin and History:Uruguay. Argentina. South America.
First recorded in NSW in 1883, recognised as a serious weed in 1911 and reached its peak infestation level of just under a million hectares in 1978. Bio control by the cochineal insect has reduced it to around 180,000 ha which is mainly in NSW where the insect is less effective. In Queensland infestations have dropped dramatically whereas in NSW they are still increasing.
Distribution:NSW, QLD, VIC.
Courtesy Australia's Virtual Herbarium.
Sub humid to semi arid areas of warm temperate and subtropical regions.
Extends from areas with and annual rainfall of less than 150 mm to those with more than 800 mm.
Soil:On a range of soils.
Plant Associations:Open woodland. Grass lands.
Edible fruit, but require careful handling to avoid the irritating bristles. Fruit used for jams and jellies. Stem segments can be candied to form a chewy sweet. In all cases the bristles must be singed with flame then the eyes sliced out.
Used in herbal remedies for whooping cough and diabetes.
Eaten by stock during droughts.
Spines used as gramophone needles.
Detrimental:Weed of conservation areas, waste land, stream banks and pasture.
Only grazed by stock during droughts when little else is available.
Spine injure the tongues and mouths of stock.
The spines are capable of causing an injury sufficiently severe to require hospital treatment. Large spines cause physical injury and fine barbed bristles penetrate the skin and are difficult to remove and lead to infection.
Forms dense patches restricting access by stock and people.
Fruit are a breeding ground for fruit fly.
Toxicity:Not toxic but causes problems by secondary infections.
Fruit may be toxic if consumed in quantity.
Legislation:Noxious weed of NSW, NT, QLD, SA, TAS and WA.
Management and Control:Stem fragments readily root making cultivation ineffective.
Thresholds:Very low in susceptible areas.
Eradication strategies:Physical removal and burning in wood fire heaps together with cultivation and removal of the root system is still used for small accessible infestations. Many infestations are not accessible and herbicides including triclopyr, picloram, hexaflurate, amitrole and MSMA are used to aid control. Use an overall spray and then cut the larger plants down the centre and re spray the cut basal section.
Stem injection is often impractical due to the large number of small segments.
Spray the infestation until just wet with 1 L Access® in 60 L diesel in spring or autumn and follow up 6 months later. If small plants become a problem use 1 L picloram + triclopyr (e.g. Grazon®) plus 1 L spray oil in 100 L water and spray the remaining plants and surrounding ground until just wet.
Small quantities of collected material may be killed by deep freezing at -200C for 48 hours.
Herbicide resistance:None reported and none likely as the main form or reproduction is vegetative.
Biological Control:Controlled mainly by the cochineal beetle and Tucumania tapiacola and to a lesser extent by Cactoblastis spp. and other introduced insects. Cochineal insects may require regular redistribution by land holders because heavy rain and cold periods reduce their numbers.
Related plants:Devil's Rope (Opuntia imbricata)
Drooping Prickly Pear (Opuntia vulgaris)
Indian Fig (Opuntia ficus-indica)
Tiger Pear (Opuntia aurantiaca) is lower, more branched and much more spiny.
Velvet Tree Pear (Opuntia tomentosa)
Wheel Cactus (Opuntia robusta)
White-spined Prickly Pear (Opuntia streptacantha)
Plants of similar appearance:Cacti.
References:Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P140. Photo.
Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P345.
Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P503.
Hyde-Wyatt, B.H. and Morris, D.I. (1980) The Noxious and Secondary Weeds of Tasmania. (Tasmanian Department of Agriculture, Hobart, Tasmania). P37.
Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne).
Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #907.1.
Parsons, W.T. and Cuthbertson, E.G. (1992). Noxious weeds of Australia. (Inkata Press, Melbourne). P359-362. Photos.
Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.