Mamillaria bocasana Poselger, Gart. Zeit. 94 (1853).
Depressed-globose, 2 to 3 cm. high: tubercles 8 mm. long, with
long axillary wool: radial spines 25 to 30, white and capillary,
10 to 25 mm. long; central spines 2 to 4, slender and naked (or
slightly puberulent), the most central one hooked (usually
upwards), 15 to 25 mm. long, the upper 1 to 3 shorter and
straight, all yellow with red tips, the hooked one often
brownish-red nearly to the base: flowers unknown: fruit green,
about 4 mm. long: seeds cinnamon-brown, oblique, broadly obovate,
with narrowly ovate basal hilum. Type unknown.
San Luis Potosi, so far as known. Poselger says, "Texas, auf der
Seira de Bocas, among rocks," which station we have been unable
to locate.
Specimens examined: San Luis Potosi (Eschanzier of 1891): also
specimens cultivated in Hort. Pfersdorff in 1869; in Mo. Bot.
Gard. in 1891; also growing in Mo. Bot. Gard. 1893.
The capillary radials give the plant a white-woolly appearance.
The younger spines at the vertex are erect and tufted. It
resembles C. grahami, but the tubercles are much more slender and
not thickened at base, all the spines are more slender, the
central hooked one is more reddish, and the fruit is much
shorter.