Melocactus intortus aka Turk's Cap Cactus

Melocactus intortus is a spiny cactus in the Cactaceae family. Its common names include melon cactus and Turk’s cap cactus. It comes from the Caribbean, where it has a broad range. This spans the Bahamas and the Turks and Caicos Islands. It also extends from Puerto Rico to the Lesser Antilles. Kew places it in the seasonally dry tropical biome. It is not native to Britain or Ireland.

This slow-growing succulent keeps its green growth year-round. It forms one stem, shaped like a ball or cylinder. Useful Tropical Plants lists a height of 1.3 feet [0.4 metres]. Its fuller account describes stems reaching 3.3 feet [1 metre]. Those stems span about 0.5–1.3 feet [0.15–0.4 metres] across. Thus, the short height entry does not cover its full size. Adult plants develop a lasting flower-bearing structure called a cephalium. This sits above the stem and can reach 3.3 feet [1 metre].

The flowers grow from the cephalium rather than the main stem. Hummingbirds and insects visit them and serve as pollinators. The species is also self-fertile. Its pink fruits have a broad, club-like shape. They measure about 0.07–0.08 feet [0.02–0.025 metres] long. People eat the fruit raw in parts of its range. People also gather liquid from the plant to ease thirst. These are recorded local uses of plants taken from the wild. Useful Tropical Plants lists no known medicinal or other uses.

In the wild, it grows in sand, gravel, and rocky ground. Its sites include coastal limestone and cliffs. Southern parts of its range also hold plants on volcanic rock. For cultivation, it needs sun and soil that drains well. It prefers acid soil with a pH below six. Established plants tolerate drought well, according to Useful Tropical Plants. Cold is a clear limit on where gardeners can grow it. Temperatures below 8°C can harm the plant.

Useful Tropical Plants reports that this cactus remains abundant in many places. It cites a 2013 IUCN assessment that lists it as Least Concern. That dated assessment describes conservation status, not garden hardiness. The same source records no known hazards. This does not establish safety for every person or pet. Its spines remain a clear physical feature to consider when handling it.