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).