Ariocarpus trigonus (F.A.C.Weber) K.Schum.
Living Rock, Star Rock
Anhalonium trigonum, Ariocarpus retusus subsp. trigonus, Ariocarpus trigonus var. minor
This species is native to Mexico (Tamaulipas, Nuevo Leon). It occurs in rocky limestone areas at elevations from 1,970 to 3,940 feet (600 to 1,200 m).
Ariocarpus trigonus, also known as Ariocarpus retusus subsp. trigonus is a slow-growing geophytic cactus with a solitary, yellowish-green stem with stiff tubercles with wooly bases, forming a rosette. It is one of the largest species in the genus. The stem is globose, more or less depressed, up to 10 inches (25 cm) tall, and up to 12 inches (30 cm) in diameter. Flowers are cream-colored to yellowish-white or yellow, occasionally with reddish midribs, up to 1.8 inches (4 cm) long and 2 inches (5 cm) in diameter, and appear from late fall to early winter. Fruits are whitish or greenish, up to 0.8 inches (2 cm) long, and up to 0.4 inches (1 cm) in diameter.
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 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 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.
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