Selenicereus anthonyanus aka Fish Bone

Selenicereus anthonyanus is a cactus that climbs. It comes from southern Mexico. Gardeners call it fish bone cactus or zig-zag cactus. It belongs to the cactus family, Cactaceae. Its range includes Chiapas, Oaxaca, Tabasco and Veracruz. It grows in lowland rainforest, often on trees. Small roots along its stems help it grip bark. It can also grow on the ground. Clearing forests for cattle ranches puts its habitat at risk.

This succulent stays green all year. It grows fast and forms groups of branches. Garden plants reach about 1.6–3.3 feet (0.5–1 metre) tall and wide. They reach this size in two to five years. Single stems can exceed 3.3 feet (1 metre) long. The smooth, flat stems are bright to yellowish green. Deep lobes on both edges give them their zig-zag shape. These leaf-like stems use light to make food through photosynthesis. Branches may climb, spread out or hang down. Small, sunken spots called areoles bear three short spines.

The scented flowers open at dusk and last one night. They bloom in spring and summer. Most bloom from late spring to early summer. Many plants seldom flower, or do not bloom at all. Flowers span about 0.3–0.7 feet (0.1–0.2 metres). Their petal-like parts are called tepals. The inner ones are cream. The outer ones are pink, red or purple. The centres have yellow tones. Bats may pollinate the flowers. How pollination works in this plant is not well understood. The dark green fruit is oval and has a scent. It bears spines and holds small black seeds.

Grow this cactus in part shade, with shelter from cold. Use humus-rich soil that drains well; loam suits it. Bark or orchid potting mix are other choices. Water it through the growing season. Let the soil surface dry before you water again. Give much less water in winter. It can cope with some drought. But it needs moist soil for growth in summer. Feed with cactus fertiliser in spring and summer. Too much feed boosts stem growth rather than flowers. It prefers 16–24°C. In winter, it needs warmth above about 4–5°C. Its H2 rating means it cannot survive freezing.

The hanging stems suit use as a houseplant. This tender cactus can also grow in conservatories and greenhouses. Its stem shape adds interest even when it has no flowers. It does not need routine pruning. Repot it every other year. Start new plants from spring cuttings or seed. Watch for mealybugs and scale insects. It has few disease problems.