Mamillaria barbata Engelm. Wisliz. Rep. 22 (1848).
Depressed-globose, about 4 cm. in diameter, simple: tubercles 8
mm. long, with naked axils: radial spines very numerous (50 to
60), in two series, 6 to 8 mm. long, the outer (about 40) slender
but rigid and white, the inner (10 to 15) a little stouter and
yellow; usually one central spine, stout and erect, hooked
downwards, brownish: flowers 18 to 20 mm. long, rose-red: fruit
oblong, 10 to 12 mm. long, green (when mature?): seeds minute,
dark brown and lightly pitted. (Ill. Cact. Mex. Bound t. 6. figs.
9-12) Type, Wislizenus of 1846 in Herb. Mo. Bot. Gard.
Central Chihuahua. Fl. May, in cultivation.
Specimens examined: Chihuahua (Wislizenus of 1846, 1850): also
specimens cultivated in Baumann's Garden in 1857, 1858; also
growing in Mo. Bot. Gard. 1893.
Dr. Engelmann observed a curious intermediate character in the
origin of the flowers of this species, the first ones of the
season appearing in the axils of the last tubercles of the
preceding year, while the later ones develop from the axils of
the first tubercles of the same season. The specimen growing in
Mo. Bot. Gard, in 1893 had 3 central spines, one or two being
hooked.