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Ariocarpus retusus subsp. trigonus (Star Rock)


Scientific Name

Ariocarpus retusus subsp. trigonus (F.A.C.Weber) E.F.Anderson & W.A.Fitz Maur.

Common Names

Star Rock, Living Rock


Anhalonium trigonum, Ariocarpus trigonus

Scientific Classification

Family: Cactaceae
Subfamily: Cactoideae
Tribe: Cacteae
Genus: Ariocarpus


Ariocarpus retusus subsp. trigonus is a geophytic cactus with a solitary, rosette-shaped stem that rises slightly above ground level. The stem is globose, more or less depressed, mostly yellowish-green, up to 10 inches (25 cm) tall, and up to 12 inches (30 cm) in diameter. Flowers are creamy-white to yellowish-white or yellow, occasionally with reddish mid-ribs, up to 1.8 inches (4 cm) long, and up to 2 inches (5 cm) in diameter.

Ariocarpus retusus subsp. trigonus - Star Rock

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USDA hardiness zones 9b to 11b: from 25 °F (−3.9 °C) to 50 °F (+10 °C).

How to Grow and Care

Plant your Ariocarpus in soil specifically formulated for cacti. You can buy a cactus mix at your local nursery. Do not use generic soil mixes because they will not provide enough aeration and drainage. Additionally, using a container without a hole, whether it is a pot or a terrarium, is a bad idea for the same reason.

Ariocarpus need a lot of sunlight. However, in hot, dry areas, they can be damaged by excessive sunlight, so you should either use a shade-cloth to limit their sun or move them out of the sun during the hottest hours of the day. In more temperate areas, direct sunlight is fine.

These cacti prefer to be kept at room temperature or slightly lower and in low humidity.

Water your Ariocarpus when it is dry, but then wait until the soil dries out completely to water it again. The amount of time this takes will vary depending on your climate and your pot's size if you use one.

Learn more at How to Grow and Care for Ariocarpus.


Native to Mexico (Tamaulipas, Nuevo Leon).


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