Origin and Habitat: Endemic to Brazil, Uruguay, Argentina, Paraguay. Now it is one of the most widely diffused prickly-pear, cultivated in Australia, South east Asia, India, South Africa, Madagascar and Spain, frequently subspontaneous after cultivation. In Southern Africa, Australia and Asia it has become a noxious invasive alien species, causing tremendous damage as these plants are able to outcompete indigenous vegetation.
Habitat: It grows in semiarid, warm temperate to subtropical areas. It occurs on most soil types including sand and calcareous soils. It grows in dry and moist sites in full sun in flats lowland, slopes, tropical forests, sandy shores, agricultural areas or wastelands from near sea level to 2000 metres elevation. It is one of the most cultivated species used to create impenetrable hedges around fields and houses-parts and formerly also cultivated for the cochineal insect in south east Asia, India, Sri Lanka and South Africa (See also Opuntia cochinelliferaSN|19862]]SN|28402]]). Opuntia monacanthaSN|28402]]SN|19862]] is perhaps best known in the form of its variety monstruosa variegata.

• Opuntia monacantha (Willd.) Haw.
• Cactus monacanthos Willd.

• Opuntia monacantha (Willd.) Haw.
• Cactus monacanthos Willd.
• Opuntia arechavaletae Speg.
• Opuntia monacantha var. deflexa Salm-Dyck
• Opuntia monacantha var. gracilior Salm-Dyck
• Opuntia monacantha f. monstruosa variegata hort.
• Opuntia monacantha var. variegata cv. Maverick variegata
• Opuntia vulgaris f. monstruosa variegata hort.
• Opuntia vulgaris f. variegata cv. Maverick hort.
• Opuntia monacantha f. monstruosa hort.
• Opuntia monacantha cv. Maverick
• Opuntia vulgaris f. monstruosa hort.
• Opuntia vulgaris cv. Maverick
• Opuntia monacantha var. variegata
• Opuntia vulgaris var. variegata hort.
• Opuntia vulgaris auct. non Mill.

• Opuntia monacantha subs. brunneogemmia (F.Ritter) P.J.Braun & Esteves
• Opuntia brunneogemmia (F.Ritter) Schlindw.
• Platyopuntia brunneogemmia F.Ritter

Description: Opuntia monacanthaSN|11631]]SN|19862]] is a very quick-growing shrubby or tree-like succulent 2-4 (6) m tall with a short trunk up to 2 dm in diameter. An early name formerly and widely applied to Opuntia monacanthaSN|19862]] is Opuntia monacanthaSN|19862]] Miller. This name is now more properly referred to Opuntia ficus-indicaSN|19862]]SN|11631]] (Linnaeus) Miller.
Stem-segments: Oblong to obovate, tapered towards the base, 10-30 cm long, 7,5-12,5 cm wide glossy green, and with an irregular margin.
Areoles: Widely separated .
Spines: 1 or 2, slender, unequal, 1-4 (6) cm long, brown towards tip and base, greyish between, spines more numerous on trunk.
Flowers: 5-7,5 long, 7,5-10 cm broad, yellow to deep orange brown, outer perianth-segments reddish. Styles and stigmas white. Ovary of 4 cm, unarmed.
Fruit: Pear-shaped, 5-7,5 cm long, 4-5 cm in diameter, reddish purple.
Seeds: Covered by a bony aril.
Chromosome number: 2n = 32

Bibliography: Major references nad further lectures
1) Hanelt Peter, Richard Büttner “Mansfeld's Encyclopedia of Agricultural and Horticultural Crops: (Except Ornamentals)” Springer, 2001
2) Lyman David Benson “The cacti of the United States and Canada” Stanford University Press, 1982
3) Christo Fabricius, Eddie Koch, Stephen Turner, Hector Magome “Rights Resources and Rural Development: Community-based Natural Resource Management in Southern Africa” Routledge, 11/Jan/2013
4) T. K. Lim “Edible Medicinal and Non-Medicinal Plants: Volume 1, Fruits” T. K. Lim Springer, 02/Jan/2012
5) Edward Anderson “The Cactus family” Timber Press, Incorporated, 2001
6) James Cullen, Sabina G. Knees, H. Suzanne Cubey "The European Garden Flora Flowering Plants: A Manual for the Identification of Plants Cultivated in Europe, Both Out-of-Doors and Under Glass" Cambridge University Press, 11/Aug/2011
7) David R Hunt; Nigel P Taylor; Graham Charles; International Cactaceae Systematics Group. "The New Cactus Lexicon" dh books, 2006
8) N. L. Britton, J. N. Rose “The Cactaceae. Descriptions and Illustrations of Plants of the Cactus Family.” Volume 4, The Carnegie Institution of Washington, Washington 1923

Cultivation and Propagation: Opuntia monacanthaSN|19862]]SN|19862]] is a low maintenance plant that tolerate considerable neglect and will naturalize. Easy to cultivate outdoor in warm dry climates.
Growth rate: it is a relatively fast growing species that can form large clumps just in a few year and fruits can be harvested 3 years after planting.
Soils: It grows well in sandy or gravely, well-drained soils. May be grown in clay soils as long as drainage is good and soils do not remain wet, it is very adaptable both in acid, neutral and basic (alkaline) soils, but prefers a pH in the range 6 to 7,5. For pot culture it needs regular cacti soil with little organic matter (peat, humus).
Repotting: Since they are big-sized plants, they need plenty of space for their roots. Repotting should be done every other year, or when the plant has outgrown its pot. Use pot with good drainage.
Watering Needs: Must be kept fairly dry in winter but likes a reasonable supply of water in the growing season, but do not overwater and allow to dry fully before watering again, tolerate dry condition but suffer if exposed to prolonged and severe drought. A position at the base of a south-facing wall or somewhere that can be protected from winter rain is best for this plant, but is however resistant to moisture and rain. Care must be taken with watering as they tends to become swollen and untidy in growth habit if given too much water and shade.
Fertilization: During the growing season enrich the soil using a fertilizer rich in potassium and phosphorous, but poor in nitrogen, because this chemical element doesn’t help the development of succulent plants, making them too soft and full of water.
Sun Exposure: Full sun (only), in semi shaded position wont produce many flowers.
Hardiness: Reputedly sensitive to frost, but less so if kept on the dry side prior to, and during, cold weather (hardy to -5° C for short periods, depending on clone). However some warmth throughout the year will increase the grower's success (minimum 5° to 8°C during rest season). In presence of high atmospheric humidity make sure that Opuntias are not exposed to freezing temperatures, or they may die. Outdoors this plant is very adaptable, as long as you avoid excessive humidity in the winter months (in good drained soils).
Garden uses: Excellent as landscape or patio plant. It is suitable for “desert” or “Mediterranean” gardens, in association with other xerophytes. Where the open air cultivation is not possible due to the climate, it is to be cultivated in pot in order to shelter it in winter.
Pests & diseases: It may be attractive to a variety of insects, but plants in good condition should be nearly pest-free, particularly if they are grown with good exposure and ventilation.
Warning: Opuntias bear spines and glochids (stiff bristles on the surface of the cladode) that can be very irritating to the skin.
Propagation: Propagated almost exclusively by cuttings of leaf pads at any time in the growing season. It may also be propagated by seeds. Seeds germinate in 7-14 days at 21-27° C in spring, remove the glass cover gradually as the plants develops and keep ventilated, no full sun for young plants! The seedlings should not be disturbed until they are well rooted, after which they can be planted separately in small pots.