[4] The subspecies name marlothii, like other succulent species, was chosen to honor the South African botanist, Rudolf Marloth.

A. f. filicaulis has been found to vary widely depending on locality, and some say the group could be classified into more than two subspecies.

Their short, sparse, upward-growing branches are grey-brown and reach 12 mm in diameter.

The sparse flowers are tubular with yellow-green sepals that are tinged with red at the tips.

Individuals from east of Vanrhynsdorp have more slender, long leaves, and grow straight branches.