Pachycereus pecten-aboriginum
| Light | Full sun; give as much light as you can |
|---|---|
| Water | Moderately in the growing season; keep dry and cool in winter |
| Soil | Deep, gritty, fast-draining mineral mix (see Soil and potting mix) |
| Temperature | Best above freezing; brief light frost tolerated once established; USDA zones 9b–11 |
| Propagation | Seed (primary); large cuttings root readily |
| Toxicity | Not known to be toxic to cats or dogs |
Pachycereus pecten-aboriginum, the hairbrush cactus, is a large columnar tree cactus native to Mexico whose fiercely spiny fruits were traditionally used by Indigenous peoples as combs and hairbrushes — a use preserved in its scientific name, which means "comb of the aboriginals". A close relative of the giant cardón, it forms a stout woody trunk topped by a candelabra of thick blue-green branches and is a familiar sight in the thornscrub and tropical dry forests of western and southern Mexico.
Description
Pachycereus pecten-aboriginum is a genuinely tree-like cactus, developing a short, distinct trunk before branching into a broad, upward-reaching crown that can reach well over head height and, with age, the size of a small tree. The branches are thick and stiffly upright, blue- to grey-green, and carry several prominent ribs lined with closely spaced areoles. Spines are short to moderate and grey, denser and stiffer on juvenile growth.
Large funnel-shaped flowers, whitish to pale pink and often reddish or brownish on the outside, open at night and into the early morning and are pollinated chiefly by bats. They give way to rounded fruits densely covered in bristly, comb-like spines — the feature that gives the plant both its common and scientific names. Beneath that spiny coat the fruit encloses sweet pulp and numerous black seeds.
Distribution and habitat
The species is widespread in western and southern Mexico, ranging down the Pacific side and through interior valleys from the northwest to the south, and reaching into the tropical dry forests of the country's southern states. It grows on rocky slopes, in thornscrub and in seasonally dry tropical forest, often as a conspicuous emergent among lower shrubs and trees.
Across this range it is a plant of hot, seasonally arid country: a long dry season through winter and spring followed by a warm summer rainy season. It is a locally common and useful plant rather than a rarity, valued historically for its edible fruit and seeds and for the practical combs made from the dried, spiny fruit.
Cultivation
This is a big, fast, sun-loving cactus, well suited to open ground in frost-free climates and to large containers elsewhere. Grow it in full sun in a deep, gritty, free-draining mineral mix that lets the substantial root system anchor a heavy plant. Water moderately and regularly through the warm growing season, always letting the mix approach dryness between soakings, then keep it dry and cool over winter — see Watering for general technique.
Given warmth, root room and light it grows quickly for a columnar cactus, so plan for eventual size and be ready to move potted plants up over time (see Repotting). In marginal climates protect it from hard or prolonged frost; young plants are more tender than established ones. Its main enemy in cultivation is the usual one — cold, wet compost that causes rot at the base.
Propagation
Seed is the primary method. Sown warm on a mineral surface and kept humid, the seeds germinate readily, and seedlings are vigorous once past the delicate early stage (see Propagation — seed). Large branch cuttings also root well: let the cut end callus for a week or more in a dry, shaded spot, then set it in barely moist gritty mix and withhold heavy watering until roots form (see Propagation — cuttings).
Common problems
- Rot — from overwatering, poor drainage or cold-wet winters; the branches or base soften and discolour.
- Frost damage — scarring or collapse of tissue after hard or extended freezes, especially on young plants.
- Etiolation — thin, pale, drawn-out growth in too little light; give the plant as much sun as possible.
- Pests — mealybugs in the areoles and scale on older stems are the usual culprits (see Pests and diseases).
See also
- Pachycereus — the genus overview
- Pachycereus pringlei — the closely related cardón
- Soil and potting mix · Watering · Repotting · Propagation — seed · Propagation — cuttings