There are several varieties of _A. Kerchovei_, of which the following are the most important:--
=A. K. diplacantha= (double-spined).* With very few distant, small teeth, often collected or united in pairs.
=A. K. inermis= (unarmed). Dwarf, with spines entirely obsolete.
=A. K. macrodonta= (long-toothed). _l._ 1-1/2ft. long, without any distinct central band, and with copious irregular grey lanceolate prickles, about 1/3in. long.
=A. K. pectinata= (comb-like). _l._ 1ft. long, 2-1/4in. broad, without any central band.
=A. lophantha= (crest-flowered).* _fl._ greenish, arranged in a dense spike 4ft. to 5ft. long; scape 7ft. to 8ft. long, its leaves brown, the lower ones 6in. long. _l._ thirty to forty in a rosette, rigid, ensiform, 2ft. to 3ft. long, 1-1/2in. broad at the middle, rather concave down the face, rounded on the back, not marked with any lines, dull green; terminal spine 1in. long; margins bordered by a very narrow continuous grey hoary line, furnished with distant linear falcate teeth, about 1/12in. long, sessile. Mexico.
=A. l. cÅrulescens= (bluish).* _l._ with a decided glaucous bloom.
=A. l. longifolia= (long-leaved). A mere variety of above species.
=A. macracantha= (long-spined).* _fl._ greenish, 2in. long, ten to twelve in a loose raceme 6in. long, all solitary on ascending pedicels 1/4in. to 1/2in. long; scape 2ft. to 3ft. long; bracts erect. _l._ thirty to fifty in a stiff rosette 1ft. to 2ft. broad, oblanceolate, 6in. to 12in. long, 1in. to 1-1/2in. broad, very stiff and rigid, very glaucous; face rather thicker in the lower half; terminal spine nearly black, very pungent, 1/2in. long; side prickles purplish-black, sub-distant, 1/8in. long, with a large point straight or slightly hooked. With a short stem, or stemless. Mexico, 1830. It has many varieties, among which are _A. Bessereriana_ and _A. flavescens_.
=A. Maximiliana= (Maximilian's).* _fl._ unknown. _l._ about twenty in a sessile rosette, oblanceolate-spathulate, 1-1/2ft. to 2ft. long, 1-3/4in. to 3in. broad; face slightly glaucous green; terminal spine pungent, brown, 1in. broad; side prickles bright chestnut brown, larger and more irregular than in _A. americana_, more hooked, and furnished with longer and sharper points, reaching 1/4in. long. Mexico. A very distinct species.