Glandulicactus
Glandulicactus is a small segregate genus of hook-spined barrel cacti native to the Chihuahuan Desert region of the United States–Mexico borderlands. Its members are best known for the long, prominently hooked central spines that give the group its most famous member the common name cat's claw cactus, and for the nectar-secreting glands tucked into their areoles — an unusual trait that gives the genus its name (from the Latin glandula, "little gland"). Only a couple of species are generally recognised, and botanists have long disagreed about whether they deserve their own genus at all: the plants have at various times been folded into Ferocactus, Sclerocactus, and the old genus Hamatocactus.
Description
Glandulicactus are small to medium solitary cacti with cylindrical to shortly barrel-shaped bodies, ribbed and usually somewhat tuberculate where the ribs break into low bumps. The defining feature is the spination: each areole carries several radial spines and one or more long, flattened central spines, at least one of which is strongly hooked at the tip like a fish-hook or a cat's claw. In some plants these hooked centrals are remarkably long relative to the body and can be dark, banded, or reddish.
Set into the felted areoles are small nectar glands that exude sugary droplets, often attracting ants — a comparatively rare feature among cacti and one of the characters used to separate the genus. Flowers are relatively small and appear near the crown, in muted brownish-red, maroon, or dull purplish tones rather than the bright colours of many desert cacti, and are followed by fleshy, elongated red fruits.
Distribution
The genus is centred on the Chihuahuan Desert and the surrounding borderlands. Plants grow on limestone hills, gravelly flats, and open desert scrub in western Texas and New Mexico in the United States and across a broad swath of north-central Mexico. There they typically grow among grasses and low shrubs that offer a little seasonal shade, in gritty, sharply drained mineral soils.
Notable species
- Glandulicactus uncinatus — the cat's claw cactus, the type and best-known species, wide-ranging across the borderlands and prized for its long hooked central spines. Its more northerly form is often distinguished as Glandulicactus wrightii.
- Glandulicactus wrightii — often treated as a variety of G. uncinatus; the Texas–New Mexico plants with especially long, hooked central spines.
- Glandulicactus crassihamatus — a central Mexican species sometimes recognised in the genus, with stout, strongly hooked central spines.
Because the genus is small and contentious, you will frequently see these same plants listed under Sclerocactus, Ferocactus, or the older name Hamatocactus in books, seed lists, and nursery labels. The plant is the same regardless of the name on the tag.
Cultivation
Glandulicactus are grown much like other small desert barrel cacti and are not difficult given the usual cactus essentials: a very free-draining, largely mineral potting mix, plenty of sun, and careful watering. Water thoroughly during the warm growing season once the mix has dried out, then reduce sharply and keep the plants dry and cool through winter, which helps prevent rot and encourages flowering.
Like most Chihuahuan Desert cacti they resent constant moisture at the roots, so a snug clay pot and a gritty topdressing both help. Handle with care — the hooked centrals catch skin and clothing readily and are difficult to pull free without breaking the spine or damaging the plant. See Repotting for general technique.
Propagation
These cacti are raised almost entirely from seed, as they are naturally solitary and rarely offset. The seed germinates on a warm, moist mineral surface in the usual way; young plants grow at a moderate pace. Slow or tricky seedlings are sometimes grafted onto a vigorous rootstock to speed them along, then grown on their own roots later. See Propagation — seed and Propagation — offsets for the general methods.
Hobby and collector notes
Glandulicactus has a modest but devoted following among collectors of hooked-spine desert cacti. The appeal is almost entirely about the spines: mature plants with long, dark, dramatically curved centrals are the ones growers seek out, and specimens are generally kept as neat single plants rather than being bred into named cultivars. Anyone buying seed or plants should be prepared to find them filed under several different genus names, and — as with all wild cacti — should buy nursery-propagated stock rather than collected plants, since the whole cactus family is listed under CITES Appendix II.
See also
- Sclerocactus · Ferocactus — genera this group is sometimes merged into
- Chihuahuan Desert
- Grafting · Soil and potting mix · Watering · Propagation — seed · Repotting