Mamillaria vivipara Haw. Syn. Succ. Suppl. 72 (1819).

Low and depressed-globose, usually proliferous and cespitose
(forming large masses), but sometimes simple: tubercles terete
and loose, lightly grooved: radial spines 12 to 20, stiff and
white, often dark-tipped, 6 to 8 mm. long; central spines usually
4 (sometimes less, often more, even as many as 8), brownish, 8 to
12 mm. long, 3 spreading upwards, the lowest stouter and shorter
and deflexed: flowers about 3.5 cm. long (large for the size of
the plant) and even broader when expanded, bright purple: stigmas
pointed with a short mucro: fruit oval, pale green, juicy, 12 to
18 mm. long: seeds yellowish-brown, obliquely obovate and curved
about the small hilum, 1.4 to 1.6 mm. long). (Ill. Cact. Mex.
Bound. t. 74. fig. 3, seeds) Type unknown.

On the northwestern plains, from the boundary provinces of
British America (western Manitoba, Assiniboia and Alberta), and
throughout the Upper Missouri region, southward through western
Nebraska to western Kansas and to the eastern foothills of
central Colorado. It is also mentioned by Howell (Cat. of
Oregon, Washington and Idaho plants), as occurring beyond the
Rocky Mountain divide in Idaho and Washington, which is probable,
but no specimens have been seen.

Specimens examined: Montana (Hayden, nos. 1854, 1855; Vernon
Bailey of 1890, near Bridger): Colorado (Hayden of 1869):
Nebraska (Rydberg 1379 of 1893, Thomas Co.): also specimens
cultivated in St. Louis in 1869; also growing in Mo. Bot. Gard.
1893.