Xerophyte

Central Spines

(8-)9-13(-15), slender, flexible, very fragile, 1.7-2.5 cm long, with a slightly bulbous bases 0.5-1 mm in diameter, and spreading in all directions usually interlocking with those of adjacent areoles. They are pure white white, or one or more central spines in each areole may be reddish (usually only at the tip), in upper and apical and younger areoles.

Hairs

Seedlings of var. canus less than 1-3 cm tall produce only flexible, hairlike white spines, these 0.5-1 cm or more long. The hairs are straight, wavy, or curved, and number about 40 per areole. They persist for several years as a dense "skirt" (1-2 cm wide) of white hairs on the lower portion of the stem. The hairlike spines become grey with age until the plants are 3-8 cm high. White and red normal spines are first produced in the apical areoles when juvenile stems are 1-3 cm long.

Note

The varietal epithet, “canus”, is a reference to the whitish aspect of the plants, after the Latin canus, "grayish-white".

Chromosome Number

2n= 22.

Ribs

14-16.

Stem

Erect, ovoid to cylindrical stems, 6-15 cm long and 3-6 cm in diameter partially obscured by spines.

Radial Spines

30-48 very slender, appressed to the stem, pure white, and 5-8 mm long.

Fruits

Greenovoid to oblong, splitting open longitudinally on at least one side and quickly drying, obscured by slender white spines, 18-20 or more in each areole.Seeds. Black nearly pear shaped, 1-1.3 mm long, and finely papillate except at the truncate bases.

Areoles

Oval 2.5-3.5 mm long.