On account of its convex top the variety becomes somewhat higher
than the species (5 to 7.5 cm.), and the flowers are sometimes
slightly longer (2 to 3 cm.).

7.Cactus meiacanthus (Engelm.) Kuntze, Rev. Gen. Pl. 260
(1891).

Mamillaria meiacantha Engelm. Syn. Cact. 263 (1856)

Hemispherical or with depressed vertex, 7.5 to 12.5 cm. in
diameter, with a broad top-shaped base: tubercles compressed, 14
to 18 mm. long: radial spines 5 to 9 (usually about 6), stout
and strongly subulate, 6 to 10 mm. long, straight or somewhat
curved, whitish or yellowish, the lower mostly a little longer,
the upper one sometimes wanting; central spine shorter and stout,
darker, straight, and porrect, turned upwards among the radials,
or rarely wanting: flowers 2.5 to 3 cm. long, reddish-white:
fruit incurved, 2 to 3 cm. long. (Ill. Cact. Mex. Bound. t.
9, figs. 1-3). Type specimens are those of the collections of
1847, 1851, 1852, and 1853, from which the original description
was drawn and all of which are in Herb. Mo. Bot. Gard.

From the Guadalupe River, Texas, to the "Great Bend" of the Rio
Grande, westward through western Texas and New Mexico; also
northern Mexico (Hemsley); Fl. May, June.

Specimens examined: Texas (Wright of 1851, 1852; Bigelow of
1853): New Mexico ("Missouri Volunteers" of 1847; unknown
collector in 1880); also specimens cultivated in St. Louis in
1853, and others growing in Mo. Bot. Gard. 1893.