Mamillaria Setispina Engelm. Mss.
Fasciculate and ascending, simple or branched at base, the stems
about 30 cm. high and 3 to 6 cm. in diameter, densely covered
with remarkably long stout spines: tubercles short and broadly
conical, with axillary wool: spines white. with black tips;
radials 10 to 12, widely spreading, very unequal, 10 to 34 mm.
long, slender and flexuous; central spines 1 to 4, more rigid and
much longer (20 to 50 mm.), the upper ones straight, the lowest
one longest and hooked (usually upwards) and often variously
curved and twisted: fruit obovate and scarlet 30 mm. long: seeds,
black and pitted. Type, Gabb 15 in Herb. Mo. Bot. Gard.
Rocky or gravelly soil, San Julio Canyon. and in the vicinity of
San Borgia, Lower California.
Specimens examined: Lower California (W. M. Gabb 15 of 1867, at
San Borgia; Brandegee of 1889, from San Borgia and San Julio
Canyon).
In his notes Mr. Gabb describes the flower as "large, 3 to 3.5
inches long, bell-shaped, of a beautiful purplish red color,"
concerning which Dr. Engelmann remarks "this would indicate a
Coryphanth, but the tubercles show no trace of a groove, and,
moreover, a withered remnant of a flower laterally attached (say
18 to 20 mm. long), so that I have no doubt that Mr. Gabb's
statement is founded on some error." It is very probable that
the flowers are scarlet and larger than Dr. Engelmann suggests.
The species is closely allied to C. roseanus, but differs in its
shorter tubercles and much longer spines. About a dozen stems
rise in a clump, about a foot high, covering an area of 2 or 3
feet. These two species represent a very distinct Lower
Californian group of cylindrical and hooked Eumamillarias. Both
probably have showy scarlet flowers and may attain considerable
length when growing upon rock ledges so as to become pendent.
The specimens of C. setispinus from San Julio Canyon are from
younger parts and show but a single long and hooked central. The
San Borgia specimens show mostly 3 or 4 centrals, the lowest one
hooked and becoming remarkably long and often variously twisted
and curved. However, I can discover no difference except such as
may be due to age.
++ Central spines present and not hooked.
+ Central spines more than one, longer than the radials, which
are numerous, white and slender (capillary or bristle-like)
(rigid in C. Halei).