According to Carter, Lavranos, Newton and Walker (Aloes the definitive guide) the Aloes can be devided in 10 groups:
A. Grass aloes B. Maculate aloes C. Stemless aloes (in small clumps, flower stems few-branched) D. Stemless aloes (in small clumps, flower stems multi-branched) E. Stemless aloes (in large clumps, flower stems few-branched) F. Stemless aloes (in large clumps, flower stems multi-branched) G. Pendulous or sprawling aloes H. Shrubby aloes (flower stems few-branched) I. Shrubby aloes (flower stems multi-branched) J. Tree aloes