Pilosocereus chrysostele
| Light | Bright light to full sun; acclimatise to prevent scorch |
|---|---|
| Water | Moderate in growth, sparingly and dry rest in winter; never leave the roots wet |
| Soil | Fast-draining mineral mix (see Soil and potting mix) |
| Temperature | Keep above about 8 °C; USDA zones 10–11 |
| Propagation | Seed and stem cuttings |
| Toxicity | Not known to be toxic to cats or dogs; the sharp spines are a physical hazard |
Pilosocereus chrysostele is a slender, branching columnar cactus from the dry interior of northeastern Brazil, prized for the dense, neatly arranged golden spines that give it its name (chrysostele, "golden column") and stand out against its green, waxy-bloomed stems. Like many members of the genus Pilosocereus, it develops woolly, hairy areoles as it matures, and its combination of tidy golden spination and glaucous, felted stems makes it a distinctive collector's cactus.
Description
Pilosocereus chrysostele forms an erect, columnar plant that branches with age, the stems relatively slim compared with many of its stouter relatives. The stems are ribbed and carry a waxy, glaucous bloom, strongest near the growing tips, over an olive- to grey-green surface. Along the ribs, closely set areoles bear short, stiff spines in warm yellow to golden tones, arranged neatly enough that the spination reads as ordered lines running up the stem.
As plants mature they produce increasing amounts of pale wool and long hairs at the areoles, particularly where flowers will form. Like other Pilosocereus, flowers arise from a lateral flowering zone — a pseudocephalium of dense wool and long hairs on one side of the upper stem — and are nocturnal and funnel-shaped, followed by fleshy fruit; the blooms are typically pale and are pollinated chiefly by bats, with moths also visiting in habitat.
Distribution and habitat
The species is native to northeastern Brazil, where it grows in the hot, seasonally dry scrub and rocky terrain of the caatinga. Plants root in gritty, sharply drained ground among rocks and low thorny vegetation, enduring a long dry season followed by a warm, wetter growing period. This background explains its horticultural preferences: strong light, warmth, sharp drainage and a genuine dry rest.
Cultivation
Pilosocereus chrysostele is a rewarding grower for anyone who can give it warmth and light. Plant it in a very free-draining, mostly mineral mix and grow it in bright light or full sun; strong light keeps growth compact and encourages the best golden spine colour and the fullest waxy bloom on the stems. Where light is weak the stems etiolate, turning greener and thinner.
Water moderately through the warm months, letting the mix dry out well between waterings, and keep the plant dry and cool over winter to prevent rot. It is frost-tender, so protect it from cold and damp; a minimum around 8–10 °C is a safe target. Take care when handling the waxy bloom, as fingerprints and marks on the glaucous surface are slow to grow out. See Watering and Repotting for general technique.
Propagation
The species is grown from both seed and cuttings. Seed germinates on a warm, humid mineral surface in the usual way for columnar cacti; see Propagation — seed. Stem cuttings root readily once the cut end has been allowed to callus for a week or two in a dry, airy spot before potting into a gritty mix — see Propagation — cuttings. Cuttings give a faster, larger plant, while seed is the route to raising many individuals and selecting for the best spine colour and bloom.
Common problems
- Rot — the usual cause of loss, almost always from overwatering, a slow-draining mix, or cold damp conditions in winter.
- Etiolation — too little light produces thin, greener growth and washed-out spination instead of compact, golden-spined stems.
- Marked bloom — the glaucous, waxy coating rubs off easily where handled or splashed, leaving marks that persist until new growth covers them.
- Pests — mealybugs (white fluff in the areoles and among the wool) and red spider mites are the pests to watch for; see Pests and diseases.
See also
- Pilosocereus — the genus overview
- Soil and potting mix · Watering · Propagation — seed · Propagation — cuttings · Repotting