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Gymnocalycium denudatum (Spider Cactus)


Scientific Name

Gymnocalycium denudatum (Link & Otto) Pfeiff. ex Mittler

Common Names

Spider Cactus


Echinocactus denudatus (basionym)

Scientific Classification

Family: Cactaceae
Subfamily: Cactoideae
Tribe: Trichocereeae
Genus: Gymnocalycium


Gymnocalycium denudatum is a small globular, usually unbranched cactus with glossy dark green body, rounded ribs and nearly harmless spines flattened against body in shape of small, white spiders. Grows up to 6 inches (15 cm) in diameter and up to 4 inches (10 cm) tall. Flowers are large, cream white, up to 3 inches (7.5 cm) wide. Blooms in spring and summer.

How to Grow and Care

Some Gymnocalyciums are shade-seeking in the wild, among shrubs or grasses, while others grow completely exposed. Some will therefore need a light shading from the sun in the hottest months, but to overdo this will result in loss of flowers.

The balance of the potting medium should be sufficient to allow good drainage, so that the plants do not sit in soggy soil for more than a day or two after watering.

Watering in the summer months, while the plants are growing well can be frequent (weekly for small plants in small pots), but always allowing the compost nearly to dry out before rewatering. Watering in the winter months at all is unwise and certainly not necessary. The difficult times are spring and autumn.

Those species which produce offsets can be readily propagated by cuttings. Gymnocalycium seed germinates well when fresh and will keep for a few years if stored in cold conditions… – See more at: How to Grow and Care for Gymnocalycium


Native to Brazil (Rio Grande do Sul), Uruguay (Melo) and probably Paraguay.


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