Mamillaria fissurata Engelm. Syn. Cact. 270 (1856).
Anhalonium fissuratum Engelm. Bot. Mex. Bound. 75 (1859).
Depressed globose or flat, top-shaped below and tapering into a
thick root, 5 to 12 cm. in diameter: tubercles (upper portion)
appressed-imbricate, 12 to 18 mm. long and about as wide at base,
the upper surface convex and variously fissured (presenting an
irregular warty appearance) even to the edges: flowers apparently
central, about 2.5 cm. long and broad, shading from whitish to
rose: fruit oval, pale green, about 10 mm. long: seeds 1.6 mm.
long. (Ill. Bot. Mex. Bound. t. 16) Type unknown; but specimens
of Wright, Bigelow, and Parry in Herb. Mo. Bot. Gard. are the
basis of Engelmann's Mamillaria fissurata.
On limestone hills, in the "Great Bend" region of the Rio Grande
in Texas, and southward into Coahuila. Fl. September-October.
Specimens examined: Texas (Wright of 1850; Bigelow of 1852;
Parry, with no number or date; Lloyd of 1890; Evans of 1891;
Briggs of 1892): also growing in Mo. Bot. Gard. 1893.
This species is very closely related to the Mexican A. kotchubeyi
Lem. (A. sulcatum Salm-Dyck), but unfortunately no type of that
species seems to be in existence, and Dr. Engelmann notes (Mex.
Bound. Rep. 75) that "it seems no living or dead specimen is at
present extant in Europe." Judging from the description, the
upper surface of the tubercles in A. kotchubeyi, aside from the
central furrow, is smooth; at least the margin is "very entire."
** Upper surface of tubercle not grooved, but usually with a
tomentose pulvillus at the tip.