Gymnocalycium baldianum aka Spider Cactus

Gymnocalycium baldianum belongs to the cactus family. Its common name is dwarf chin cactus. It comes from northwest Argentina. This includes the mountains of Catamarca Province. It grows among grass at heights of 1,640–6,562 feet [500–2,000 metres]. Its small wild range forms one area, not separate patches. People who collect plants threaten some sites. Fires affect others.

This small cactus most often grows as a single stem. Its round body has a flat top and seldom forms offsets, or side shoots. Garden plants reach about 0.33 feet [0.1 metres] tall and wide. LLIFLE records wider stems. These reach 0.43 feet [0.13 metres] across. Stems range from grey-brown to blue-green. Some are near blue-black. Nine to eleven ribs bear round bumps called tubercles. Deep grooves divide these bumps. The areoles sit low, each bearing five to seven thin radial spines. These may point straight out or bend toward the stem. They are pale brown or grey, with red near their bases.

Funnel-shaped flowers grow at the crown, or top of the stem. They bloom in summer, starting in early summer. They span about 0.10–0.13 feet [0.03–0.04 metres]. They open wide in sun. Flowers can be deep pink, crimson or purple-red. LLIFLE also records white, pink and orange blooms. Purple stamens ring pale yellow-white anthers and a stigma with six lobes. Young plants may bloom just one year after sowing. The long green fruit splits along its length when ripe.

Grow it in cactus compost that drains well. Give it good airflow. RHS advises bright light under glass, with the light filtered. LLIFLE gives a range from full sun to light shade. Give modest amounts of water during growth. Then keep it almost dry through winter. RHS suggests a balanced liquid feed during growth. Give this every two or three weeks. Its UK hardiness rating is H2, so avoid frost and freezing. LLIFLE reports that dry plants can withstand 14°F [-10°C]. These sources differ on how much cold it can take. RHS gives the more cautious guide. RHS puts maturity at five to ten years. LLIFLE says it grows fast.

Its small size suits pots, patios and growing under glass. The blooms give colour without a large plant. It needs no pruning. LLIFLE says its care is easy. Sow seed in early spring at 66–75°F [19–24°C]. Watch for mealybugs. RHS reports few disease problems. The supplied sources give no evidence of edible uses. They also give no evidence of toxicity.