Mammillaria polythele aka Stachellos

Mammillaria polythele is a cactus in the family Cactaceae. It also goes by the name pin-cushion. Its native range lies in Mexico, from Jalisco to Veracruz. It grows in dry shrubland and also in oak woods. Wild plants can grow among dense plants in partial shade. LLIFLE records it in Hidalgo, Querétaro, and Guanajuato. There, it grows at 5,580–7,870 feet [1,700–2,400 metres] above sea level.

This cactus has one long, round stem. Most stems stand upright, though some spread along the ground. They range from dull green to a dark blue-green. The usual height is 1–2 feet [0.3–0.6 metres]. Rare plants reach about 2.6 feet [0.8 metres]. Stems measure about 0.16–0.49 feet [0.05–0.15 metres] across. Rare stems reach 0.56 feet [0.17 metres] across. Raised tubercles crowd the surface in spiral rows. Wool fills the gaps near the growing tip. Older parts lose this wool and look more bare. The tubercles bear two to four spines.

Flowers form a ring near the stem tip in summer. Their colour ranges from rose pink to pink-purple. Each bloom has narrow petals that end in sharp points. Flowers measure about 0.03–0.05 feet [0.010–0.014 metres] across. Even small plants may bloom. LLIFLE reports flowering at about 0.16 feet [0.05 metres] tall and wide. The fruits have a club shape. They turn dull red or purple and hold small brown seeds.

Give this plant bright light and good air flow. Use a loose cactus mix with at least half grit. Keep peat and other rich organic matter low. Water only once the soil feels dry. Let water drain out fully before watering again. Avoid wetting the spines, since trapped water can cause rot. Keep the plant dry through winter and protect it from frost. LLIFLE reports survival at −5°C when kept dry. A dry winter rest helps it flower and survive. Use small pots and repot every two to three years.

People grow this cactus for its form and flowers. LLIFLE also records local use as food. The evidence does not name edible parts or establish toxicity. Wild populations face illegal collection, goat grazing, and woodland loss. Despite these pressures, LLIFLE describes the species as widespread and abundant.