Xerophyte

Seeds

Black or dark brown, glossy, bowl to helmet shaped about 2 mm long, 3 mm broad.

Roots

The underground body is fleshy, turnip-like, with fine diffuse roots.

Flowers

Apical, diurnal, radial, 3-5 cm long, 5-9 cm in diameter opening widely, yellow with orange/red throats. Ovary and tube very short, densely covered with thin, bristle-like, black tipped scales and with cobwebby wool in axils.

Blooming Season

Spring to summer and each flower lasts for one or two days only, but the plant may flower at any time during the warmer months of the year if adequate water is provided.

Spines

Not any.

Ribs

The stem is typically divided by very narrow but distinct vertical grooves into 8 broad ribs. The ribs are very low, almost flat on top, forming triangular sections with no cross-grooves. The normal rib number eight is very stable in wild specimens, independent of the age of the plant, but in cultivation selected cultivars and hybrids can have from 4 to 13 ribs.

Stem

Non-branched, much depressed, disc-shaped to low dome-shaped, grey-green to dull green (unless stressed), mature plants up to 7 cm tall, 5-16 cm broad, dotted with a mosaic of extensive white spots and V-shaped subtending each areole that make the plant look intensely maculate. Cultivated plants possess sometimes very dense and big hairy scales.

Fruits

Oval to round, about 1,5-2 cm long, green, pinkish or greyish-red densely covered with spines and dull-white wool, becoming dry and finally breaking off at or near base (not opening above the base).

Areoles

Round, prominent, 3-12 mm in diameters, forming a line up to the centre of each rib, felted to hairy, white, creamy, dirty-yellow till straw-coloured, then grey. Normally few millimetres apart, but in cv. Rensei areoles are very close one to each other, almost touching, and forming an almost continuous line.