Coryphantha nickelsiae aka Nickels' Cactus

Coryphantha nickelsiae is a small cactus in the Cactaceae family. Its common names include Nickels' cactus and Nickels' pincushion cactus. Its native range runs from southern Texas into northeastern Mexico. There, it grows in Coahuila, Tamaulipas, and Nuevo León. It comes from desert and dry shrubland habitats. Plants may grow alone or form dense, low mats.

The stems sit deep in the ground, with rounded tops. Their exposed parts reach 0.13–0.36 feet [0.04–0.11 metres] tall. Each stem measures about 0.16–0.23 feet [0.05–0.07 metres] across. These measurements describe single stems, not the whole mat. Stems range from pale to dark green, sometimes with a blue-grey cast. Older plants may turn purple. Raised tubercles cover the stems and carry fine, crowded spines. These overlap and can hide much of the green surface. Most turn white with age, though some remain brown or nearly black. Older plants may develop flat, ribbon-like upper spines.

Plants produce large yellow flowers in cultivation. Green or grey-green fruits follow, with round to oval shapes. A dried flower remnant stays attached to each fruit. The small seeds start orange and turn brown as they dry. Growth is slow rather than quick. Plants take about eight to twelve years to gain their mature form. This small cactus offers both dense spine cover and showy flowers.

Grow it in a loose cactus mix with sand and grit. It needs modest watering while growing and dry conditions in winter. Also keep it dry when nights stay below 10°C. Too much water can cause rot, which may kill mature plants. Take extra care with watering after planting and in larger pots. It needs little feed and can grow in poor soil. Excess feeding can promote soft growth that is prone to fungal disease.

Warm winter conditions are the safer choice for cultivation. A winter minimum of 5°C is recommended. Fully dry plants may survive brief cold near −5°C. Avoid frost rather than relying on that limit. Seed provides a means of propagation in warm spring conditions. Use fine, sandy soil that drains well for sowing. Young seedlings need more moisture at first, then less as they grow.