Globose or ovate globose, 2 to 2.5 cm. high and 1 to 2 cm. broad: tubercles 4 mm. long, about 2 mm. in diameter, with naked axils: spines 40 to 60, in many series, very unequal, 2 to 4 mm, long, white and pilose, the upper exterior usually longer than the rest, the innermost usually much shorter: flowers 12 mm. long, whitish or pinkish (petals with red median band): fruit 1 to 2 cm. long: seeds about 1 mm. long, blackish and conspicuously pitted. (Ill. Cact. Mex. Bound. t. 3). Type, the specimens of Wright in Herb. Mo. Bot. Gard.
From western Texas ("west of time Pecos, on low limestone hills, among herbage") to Arizona and Chihuahua. Fl. April, May.
Specimens examined: Texas (Wright 121, also of 1852; Parry of 1852): Arizona (Miller of 1881): Chihuahua (Pringle 213, 250,258): also specimens cultivated in St. Louis in 1852 and 1855.
11. Cactus lasiacanthus denudatus (Engelm.).
Mamillaria lasiacantha denudata Engelm. Cact. Mex. Bound. 5 (1859).
Larger, 2.5 to 3.5 cm. in diameter, with longer tubercles (5 to 6 mm.), and more numerous (50 to 80) longer (3 to 5 mum.) spines which are naked or nearly so. (Ill. Cact. Mex. Bound. t. 4) Type, Wright specimen in Herb. Mo. Bot. Gard.
From western Texas (with the species) to Coahuila.
Specimens examined: Texas (Wright of 1852): Coahuila (Palmer of 1880).
In the Syn. Cact. Dr. Engelmann merges this variety with the species, and has been followed in this by subsequent writers, but the characters seem so (distinctive that its varietal rank has been restored.
12. Cactus micromeris (Engelm.) Kuntze, Rev. Gen. Pl. 260 (1891).