Pilosocereus leucocephalus aka Woolly Torch

Pilosocereus leucocephalus is a tall cactus in the Cactaceae family. Its range runs from Mexico through Guatemala to Honduras. It grows in tropical lands with a dry season. Wild plants live in dry scrub and forests. These include forests that shed their leaves each year. Seeds can sprout beneath other plants or in rock cracks. People also call it woolly torch or old man of Mexico.

This cactus forms upright columns and may branch near its base. RHS gives a garden height of 13–26 feet [4–8 metres]. Its spread reaches about 1.6–3.3 feet [0.5–1 metre]. LLIFLE describes plants reaching 6.6–20 feet [2–6 metres]. Short trunks support stems with seven to nine broad ribs. Young stems have a pale blue, waxy look. Older stems become dark green. Dense white hairs cover the upper spine-bearing pads, called areoles. Brown or yellow spines turn grey as they age.

Older plants grow flowers near the tops of their stems. More dense hair marks the areas that bear flowers. Blooms range from tubes to bells, with pale pink interiors. RHS describes yellow throats, while LLIFLE notes reddish-green outer parts. Plants flower in separate flushes during the warmest months. Chicago Botanic Garden records bloom from July to August. Heat, rain, and plant size affect the timing of flowers. Bats do most of the pollination in the wild. Other visitors also help plants set fruit. Round red fruits hold red flesh and black seeds.

Grow this cactus in full sun with fast-draining sandy soil. RHS lists acid or neutral soil as suitable. It resists drought, but needs more water during summer growth. Summer feeding also helps support new growth. RHS advises keeping it at 11°C or warmer. Its UK hardiness rating is H1B. Chicago Botanic Garden lists USDA zones 10–11. A sheltered outdoor spot suits it during warm summer months. It serves as a bold focal plant or container specimen. RHS gives five to ten years to reach mature size. It needs no pruning; summer propagation uses seeds or stem cuttings.

Too much water can cause rot, most of all in cool weather. Aphids, mealybugs, spider mites, and whiteflies may attack it. Other listed pests include capsid bugs, earwigs, and eelworms. Tropical Plants Database reports that people eat the fruit raw. That source records no known hazards or medicinal uses. It lists the species as Least Concern. Local clearing for farms and cattle still threatens some wild sites.