Echinocereus websterianus aka Isla San Pedro Cactus

Echinocereus websterianus is a cactus in the family Cactaceae. Its common names include Webster’s hedgehog cactus and San Pedro Nolasco hedgehog cactus. Kew records its native range on San Pedro Nolasco Island, Sonora, Mexico. It grows in desert or dry shrubland. LLIFLE questions reports of a wider range on the Baja California mainland.

This succulent subshrub forms upright stems and can develop large clumps. Some plants produce about 50 stems, with branches growing from the base. In pots, a plant may keep one stem for years. Stems reach about 2 feet [0.6 metres] long. Each measures roughly 0.2–0.26 feet [0.06–0.08 metres] across. The light green stems have 18–24 low, clear ribs. Some ribs bear small bumps. Closely spaced areoles carry thin, curved spines. Most spines start gold and turn brown with age. Some plants have white spines instead. Each areole has about 10–14 spreading radial spines. It also carries six to eight upright central spines. These can be hard to tell apart from the radials.

Flowers open during the day near the stem tips. They have a funnel shape and a short tube. Colours range from near-white through pink to violet, with yellowish blooms also reported. The throat is white or yellow. Flowers reach about 0.2 feet [0.06 metres] long. They span about 0.1–0.13 feet [0.03–0.04 metres]. LLIFLE gives June to July as the flowering season. Each bloom stays open for two or three days. Seed-grown plants may take seven to ten years to flower.

Grow this cactus in strong sun and a pot with good drainage. A deep pot suits its roots. Water it regularly from March through October. Keep winter conditions dry and cool, with as much light as possible. LLIFLE links this winter rest with better flowering. It advises avoiding frost, despite reporting brief survival at 23°F [−5°C]. Growth is slow, but the source describes cultivation and propagation as easy. Growers can raise plants from seed or root cuttings.

Its flowers and gold spines give it value as a pot specimen. Handle it with care when moving or repotting it. Spine clusters break away with slight contact and leave lasting marks. Such damage need not mean the plant received poor care. Winter rot is a concern where drainage or moisture control fails. Old flower remains can also lead to stem rot. Tall stems can be cut and rooted again. The remaining base can produce new shoots for further cuttings.