Opuntia polyacantha - Many-spined prickly pear

Opuntia polyacantha, the Plains Prickly Pear, is a species of cactus native to the vast plains of the American West and southern Canada. Valued for its exceptional hardiness and colourful flowering, it makes an excellent choice for dry gardens, rockeries, or landscaping in many regions. Striking in a minimalist setting and spectacular against a backdrop of rocks, this plant, which spreads into prickly mats, naturally structures desert or contemporary landscapes.

Belonging to the Cactaceae family, Opuntia polyacantha has several botanical synonyms, including Opuntia erinacea and Opuntia hystricina. Its natural range extends from southern Canada, particularly British Columbia, to northern Mexico, covering a vast area of the United States, from the Great Plains to the desert regions of the Southwest. This cactus forms dense clumps reaching up to 15 cm in height and several metres in width. Its growth is relatively fast for a cactus, allowing it to quickly colonise dry areas. The "pads" or cladodes are flattened, ovate to almost round in shape, measuring between 5 and 12.5 cm long and 3.5 to 10 cm wide, with a thickness of about 1 cm. They are blue-green in colour and devoid of hairs. The closely spaced areoles bear almost invisible yellow glochids and 6 to 10 needle-like, straight or slightly curved thorns, measuring from 1 to 12.5 cm long. Flowering, which occurs from May to July, takes the form of 4.5 to 8 cm diameter flowers, usually yellow, though red variations exist depending on the strain. The fruits ripen in late summer and are ovoid, measuring 2 to 4 cm long, and turn brown at maturity. Broken segments or "pads" can root easily, promoting the vegetative spread of the species. The species name polyacantha comes from ancient Greek: poly- meaning "many" and acantha meaning "thorn". This name refers to the abundance of thorns on this species, which provide effective protection against herbivores. The fruits of Opuntia polyacantha are edible. Traditionally, Indigenous peoples consumed these fruits raw, cooked, or dried. The fruits, called "tunas", can be eaten fresh after peeling to remove the thorns or processed into jams, jellies, and beverages. The young pads, or "nopales", are also edible and can be boiled or fried after removing the thorns. The seeds can be dried, roasted, and ground into flour for use in culinary preparations. It is essential to handle the fruits and pads with care to avoid the glochids, those fine, irritating thorns.

Cultivable in all regions in well-drained soil and full sun, this "cactus" thrives in any stony, rocky, or sandy soil. It is a low-maintenance plant even in harsh climates under these conditions. Plant Opuntia polyacantha in a large rockery, gravel bed, or arid slope. It will be perfect in a stark, rocky setting with hardy columnar cacti like Cleistocactus strausii, Agave ovatifolia (also very hardy), and Hesperaloe parviflora. It can also be paired with other dryland plants like giant fennel. It is advisable to keep it away from pathways and children, due to its formidable thorns, as well as the transparent, almost invisible ones that can easily penetrate the skin and are difficult to remove.