Gordon Rowley summarises the impact of recent research on the Asphodelaceae Subfamily Alooideae: Aloe, Haworthia, Gasteria and related genera. Their evolution as pictured in a family tree is strongly rooted, but their classification in a hierarchy of taxonomic categories divides opinions.

Considerations of morphology and geographical distribution suggest that two recently described infraspecific taxa of Sansevieria pinguicula P.R.O. Bally were given inappropriate ranks. It is proposed that subspecies disticha, occurring together with the type in habitat and differing in only one character, should be reduced to the rank of form. It is proposed that variety nana, which occurs at some considerable distance from the type and differs in three characters, should be raised to the rank of subspecies.