Xerophyte

Habit

Solitary, slow growing geophyte cactus with tubercles slightly projecting above ground level. The flat tuberous body is below the soil.

Description

Ariocarpus retususSN|2079]]SN|2079]]us commonly known as the "Star Rock" is one of the largest species that distinguishes for the fat triangular tubercles forming a starry rosette. It is a widespread and extremely variable plant. Tubercle size and shape vary widely, a terminal areole is sometimes present at the tip. The vast amount of phenotypic variation in the species has led to the erection of several variants and has received numerous unnecessary names of no botanical value.

Roots

Tap root.

Note

All of the Ariocarpus seedlings are spiny and quite different from adult specimens, though the spines are feather-like.

Tubercles

Leaf-like, divergent, erect, basally compressed, usually becoming attenuate at the apices, convex or nearly flattened adaxially and often with shallow adaxial undulations or wrinkling, not fissured, 1,5-4 cm long, 1-3,5 cm wide, nearly as wide as long.

Flowers

Diurnal 4-5cm in diameter, 2-4,2 cm long, white to pink (or magenta), occasionally with reddish midribs.

Blooming Season

Autumn.

Stem

Grey, or blue-green, flattened, globose, rounded on top, 3-12 cm high, 10-25 cm in diameter.

Fruits

White, green, or rarely pinkish, 10-25 mm long, 3-10 mm in diameter.

Areoles

At the tips of the tubercles, rounded, 1-5 mm in diameter often only on younger specimens.