The same thing may be observed in many non-mimetic butterflies, for instance in all our species of Vanessa, in which the under side shows a grey-brown or brownish-black protective coloration, but we do not yet know with certainty what may be the biological significance of the gaily coloured upper surface.英文原著 · 《Darwin and Modern Science》
The covering of stout bushy interlocking spines is like that of var. deserti, but the black and reddish coloration gives a decidedly different appearance. On account of this appearance of a reddish-black brush the plant has been popularly called "foxtail cactus." The decidedly pink flowers were sent by Mr. Parish from specimens growing in cultivation in San Diego, and are not from the original collection of Mr. Alverson.英文原著 · 《The North American Species of》