Mamillaria echinus Engelm. Syn. Cact. 267 (1856).
Globose or subconical, 3.5 to 6.5 cm. in diameter, simple:
tubercles terete, conical, grooved above, 10 to 12 mm. long:
radial spines 16 to 30, pectinate, straight or little curved,
rigid and appressed (interwoven with neighboring clusters),
ashy-white (often dusky at apex), 8 to 12 mm. long, the uppermost
longer (12 to 20 mm.); central spines 3 or 4, the upper ones
turned upward and intermixed with the radials, the lower one very
stout, 15 mm. long, subulate from a very thick bulbous base,
straight (rarely slightly curved) and porrect (deciduous in old
specimens): flowers 3 to 5 cm. long: fruit oval, elongated, about
2 cm. long, green: seeds elongated-obovate. brown and smooth,
about 1.8 mm. long. (Ill. Cact. Mex. Bound. t. 10) Type, the
Wright and Bigelow specimens in Herb. Mo. Bot. Gard.
On limestone hills, from the Pecos River, southwestern Texas, and
southern New Mexico, westward to the Rio Grande (from Presidio
del Norte northward). Fl. June.
Specimens examined: Texas (Wright of 1849, 1851, 1852; Bigelow of
1852; Engelmann, with no number or date; Evans of 1891).
The characteristic appearance of the plant is given by the very
stout and straight central spine standing in each cluster
perpendicular to the plant body. The range of this species,
between the Pecos and the upper Rio Grande, suggests another
separated group, such as is presented by C. scolymoides sulcatus
to the east, between the Brazos and Nueces. Very frequently
specimens of C. echinus occur in which some of the tubercles do
not develop central spines, and then the spine characters
resemble those of C. radians. In C. radians, also, an occasional
porrect central spine is found. These intergrading forms I have
only seen in Mexican material. For discussion of relationships
see under C. scolymoides.
** Flowers red.
+ Central spine solitary or sometimes wanting.
51. Cactus dasyacanthus (Engelm.) Kuntze, Rev. Gen. Pl. 259
(1891).
Mamillaria dasyacantha Engelm. Syn. Cact. 268 (1856).
Subglobose, 3.5 to 6.5 cm. high, simple: tubercles slender and
terete, spreading, lightly grooved even to the base, 8 to 10 mm,
long: radial spines 30 to 50, mostly in two series, straight and
loosely spreading, the exterior ones (25 to 35) capillary and
white, 6 to 18 mm. long, the interior ones (7 to 13) stiffer
(setaceous), longer and darker and black-tipped; the central
spine straight and porrect, 12 to 20 mm. long, often wanting:
flowers small, red: fruit ovate, small (8 to 10 mm. long?): seeds
globose-angled, almost black, pitted, 0.8 to 1.2 mm. long (Ill.
Cact. Mex. Bound. t. 12. figs. 17-22) Type, Wright 110 in Herb.
Mo. Bot Gard.
From Eagle Pass, Texas, westward to El Paso and southern New
Mexico, and southward into Chihuahua.
Specimens examined: Texas (Wright 110 of 1852): New Mexico (Vasey
of 1881; Mearns of 1892, in Big Hatchet Mountains) Chihuahua
(Pringle 251 of 1885, in part).
Pringle 251 as distributed to Nat. Herb. is C. tuberculosus.