=A. vivipara= (viviparous).* _fl._ greenish yellow, 1-1/2in. to 2in. long, often changed into bulbillæ, which bear lanceolate leaves 6in. long before they fall and take root; inflorescence reaching a height of 20ft. or more, the deltoid panicle about a quarter of the length of the scape; corymbs on stout peduncles, pedicels short. _l._ twenty to fifty in a dense, shortly caulescent rosette, ensiform, 2ft. to 3ft. long, 1-1/2in. to 2in. broad at the middle, whence it gradually narrows to the point, dull green when mature, thin but firm in texture, flat or channelled down the face; terminal spine firm, brown, 1/2in. long; side teeth brown, hooked, 1/12in. or less long. A very widely spread species throughout tropics of the Old World, 1731. SYNS. _A. cantula_, _A. bulbifera_.
=A. Warelliana= (Warell's).* _l._ about thirty in a rosette, oblong-spathulate, 9in. to. 10in. long, 3in. broad above the middle, narrowed to 2in. above the dilated base; face nearly flat, green, scarcely at all glaucous, tipped with a strong brown channelled spine 1in. long; border margined with close, very short teeth, dark purple when mature. Mexico. A rare but very handsome species.
=A. Wislizeni= (Wislizenius's). _fl._ 2-1/2in. long; panicle thyrsoid, its branches 3in. to 6in. long; pedicels very short; scape 12ft. high. _l._ about thirty in a dense, rigid, sessile rosette, which is under 2ft. broad, oblong-spathulate, 3in. to 3-1/2in. broad above the middle, very glaucous, concave in the upper part; terminal spine hard, pungent, dark brown, 1in. long, and decurrent down the border a little; side prickles 1/8in. long, dark purple, moderately close, those below the middle of the leaf smaller and curved downward. Mexico, 1847.
=A. xalapensis.= Synonymous with _A. polyacantha_.
=A. xylacantha= (woody-spined).* _fl._ green, 1-1/2in. long; spike dense, rather shorter than the scape, its bracts linear-subulate; scape 5ft. to 6ft. long, its bracts subulate, all ascending, the lower ones 6in. to 8in. long. _l._ not more than twenty in a stemless rosette, ensiform, diverging irregularly and often curving, 1-1/2ft. to 3ft. long, 2in. to 3in. (rarely 4in.) broad at the middle, narrowed gradually upwards, a slightly glaucous dead green, marked with a few darker green lines on the back, furnished with a broad continuous horny border and a few very large irregular hooked teeth, often united or collected in pairs, 1/2in. to 3/4in. long, and 3/8in. to 1/2in. broad; terminal spine brown, pungent, 1in. long. Mexico. A long-known, widely-spread, and distinct species. SYNS. _A. amurensis_ and _A. Vanderdonckii_.