About Cylindropuntia imbricata (Haw.) F.M.Knuth
Cylindropuntia imbricata (Haw.) F.M.Knuth, commonly called cane cholla, has an above-ground structure made up of much-branched cylindrical stems, with end joints that measure around 3 cm (1.2 in) in diameter. Unlike the joints of some other cholla species, these joints are hard to detach. The stems have a distinct highly lumpy (tubercular) texture, marked by a pattern of long oval lumps. Most individuals reach a typical height of around 1 m (3 ft), but exceptional specimens can grow up to 4.6 m (15 ft) with a trunk diameter of 25 cm (9.8 in). The overall width of the plant is often similar to or slightly greater than its height.
Stems are covered in clusters of up to around 10 red to pink spines, which can reach 3 cm (1.2 in) long. These spines are barbed and sharp enough to easily penetrate leather gardening gloves. Both stems and fruits also have many small 1 mm (0.04 in) long spines called glochids that easily detach and stick to skin. This species produces two distinct types of stem (cladodes): long plagiotropic cladodes, which bear flowers at their tips and fall off the plant after a few years, and long orthotropic cladodes, which primarily provide structural support and conduct water and nutrients, and remain on the plant permanently. Plagiotropic stems grow in a star- or crown-like pattern around a central orthotropic stem.
Cylindropuntia imbricata blooms in late spring or early summer. Its flowers are purple or magenta, rarely rose-pink, and measure around 5 cm (2.0 in) wide. The fruits are yellowish, tubercular like the stems, shaped roughly like a cone frustrum, with a hollow at the wide end where the flower detached. Fruits are often mistaken for flowers, the plant retains them through the winter, and they are dry and bland in flavor. Indigenous peoples of Arizona and New Mexico are recorded to have eaten these fruits.
In addition to reproducing sexually, this tree cholla can also reproduce vegetatively when stem joints fall to the ground and take root. This makes the species hard to control once it spreads. Animals help spread the species both by defecating seeds away from parent plants and by carrying detached stem joints stuck to their hides long distances. Some cattle, called "cholla eaters", learn to consume cholla fruits despite the pain from spines. Waves of invasion typically occur four to five years after a period of drought combined with grazing, likely because this combination exposes open soil where stem joints can successfully take root.
The native range of cane cholla covers arid regions of Nevada, Arizona, New Mexico, Colorado, Oklahoma, Kansas, and Texas in the United States, extending south into Mexico to Durango, Zacatecas, and San Luis Potosí. It grows at altitudes between 1,200 and 2,300 m (3,900 to 7,500 ft), and is unusually cold hardy for a cactus, rated for USDA Zone 5A. In parts of its native range, often just below the pinyon-juniper vegetation belt, it can grow in great abundance. In these areas, it is surrounded by low grasses and forbs that stay brown most of the year, and cane cholla is conspicuous as the only tall green plant present. It may grow in dense thickets, or spaced several times its width apart in open "cholla gardens". This species is a declared noxious invasive weed in Australia, where it occurs in old mining sites and along watercourses. It is known there by the common names Devil's rope cactus or Devil's rope pear. It is a declared noxious weed in New South Wales, and also grows in Queensland, the Northern Territory, Victoria, and South Australia.
In its native range, the fruits of Cylindropuntia imbricata are eaten by a variety of wild birds and mammals, including pronghorn, desert bighorn sheep, and deer. The dense thorny growth of the plant provides protective escape cover for many small animals. The leafcutter bee Lithurgus apicalis has been observed pollinating its flowers.
This species is sometimes grown as an ornamental plant. When dead stems decay, they leave a hollow wooden tube marked with a pattern of lengthwise slits. These hollow tubes are sometimes used to make walking canes or decorative curios. Historically, the Roman Catholic Penitentes of New Mexico tied fresh stems to their bare backs during Holy Week processions. The Zuni people use this variety for ceremonial purposes.
