Cylindropuntia
Cylindropuntia is a genus of shrubby to tree-like cacti native to the deserts and dry scrub of the Americas, commonly known as the chollas (pronounced "CHOY-yah"). They are opuntioid cacti — close relatives of the prickly pears — but where a prickly pear has flat pads, a cholla has segmented, cylindrical stems. Many species are notorious for their barbed, easily detached joints and the papery spine sheaths that give their spines a glinting, straw-coloured coat.
Description
Chollas are built from series of cylindrical stem segments, or joints, that branch to form anything from a low, spreading shrub to a small tree several metres tall. The joints are ribbed lengthwise into raised tubercles, each bearing an areole from which the spines emerge. In most species those spines are clothed in a distinctive papery sheath — a thin, retained epidermal cover that can be silver, straw, gold or pinkish, and which lends the whole plant its characteristic shimmer in low sun. This sheath is the feature that most reliably separates Cylindropuntia from Opuntia, whose spines have no such covering.
Like all opuntioids, chollas carry glochids — tiny, barbed bristles clustered at the areole that detach at the lightest touch and lodge painfully in skin. Many species take this further: whole joints break away with barely any contact, hitching a ride on a passing animal before rooting where they fall. This is the trait behind the jumping cholla nickname, and it doubles as an efficient means of vegetative spread.
Flowers appear at the tips of the joints and are typically cup-shaped in yellow, green, bronze, pink or magenta, followed by fleshy or dry, often spiny fruits. Some species retain their fruits over winter, and a few produce chains of sterile fruit that grow one from another.
Distribution
Cylindropuntia is a New World genus, centred on the arid regions of the southwestern United States and northern Mexico, with its native range extending south-east into the West Indies. They are classic plants of the Sonoran, Chihuahuan and Mojave deserts, thriving on well-drained slopes, desert flats and gravelly scrub. Several species have been carried well beyond that native range — chollas are declared invasive weeds in parts of Australia and South Africa, and have been introduced into western South America, precisely because a single dropped joint can establish a new plant.
Notable species
- Cylindropuntia bigelovii — the teddy-bear cholla, densely clothed in pale, backlit spines; among the most readily detaching (and most feared) of the "jumping" chollas.
- Cylindropuntia fulgida — the chain-fruit or jumping cholla, a tree-like species with hanging chains of proliferating fruit.
- Cylindropuntia imbricata — the tree cholla or cane cholla, a hardy, magenta-flowered species that ranges far north and tolerates hard frost.
- Cylindropuntia spinosior — the walkingstick or cane cholla, valued for its colourful spring flowers and sturdy, latticed dead wood.
- Cylindropuntia leptocaulis — the desert Christmas cholla, a slender, twiggy plant carrying bright red fruit through the winter.
Cultivation
Chollas are among the easiest cacti to keep, asking mainly for sun and sharp drainage. Give them the brightest position you can and a gritty, fast-draining mineral mix; they resent sitting wet far more than they resent going dry. Water generously during the warm growing season once the soil has dried, then keep them nearly bone-dry through winter. Many species are surprisingly cold-hardy — C. imbricata in particular shrugs off frost well into temperate gardens — while desert species prefer to stay above freezing. See Watering and Repotting for general technique.
The one real caution is handling. The barbed spines and glochids make chollas genuinely difficult to work with; use thick gloves, folded newspaper or tongs when repotting, and site them well away from paths, pets and children. A detached joint dropped in a pot will usually root of its own accord, so tidy up fallen segments unless you want more plants.
Propagation
Vegetative propagation could hardly be simpler: a detached joint left to callus for a few days on dry, gritty mix will root readily — the same mechanism the plant uses in the wild. This is by far the most common method in cultivation. See Propagation — cuttings for the general approach. Species can also be raised from seed, though germination is slower and less predictable, and seed is mostly of interest for producing new plants and preserving genetic variety.
Hobby and cultivar notes
Chollas are more often admired in habitat or grown as tough landscape plants than fussed over as show specimens, and named cultivars are relatively few. Collectors prize the species with the showiest spine sheaths — the silvery, backlit spines of the teddy-bear cholla being a perennial favourite — and the skeletal, latticed dead wood of the larger species is popular in craft and décor. Because a single joint roots so easily, plants are readily shared among growers. A handful of intergeneric and natural hybrids exist, but the genus is grown chiefly for the striking architecture and spination of the wild species themselves.
See also
- Opuntia — the prickly pears, the flat-padded opuntioid relatives
- Grafting · Soil and potting mix · Watering · Propagation — cuttings · Pests and diseases