The specific epithet perfoliata, is derived from per, meaning 'through' and folia, leaves, and alludes to the leaf bases surrounding the stem, which appears to pass through the substance of the long-lived evergreen leaves. The variety name indicates that the plants are smaller than in the other varieties.

Crassula perfoliata was named by Carl Linnaeus in 1753.

The var. minor was named by the well-known succulent student Adrian Haworth in 1821 (Britain) who grew plants from an unknown source. There are four known varieties:

• The var. minor is at once distinguished from its close relatives by its small size (only 1 to a few branches), the leaves which are often mottled and grey-green, distinctly sickle-shaped and not channelled at the base, and the red to pink flowers which are up to 7 mm long.
   
• The var. perfoliata (from the eastern Nama Karoo) is up to 1.3 m tall with erect lance-shaped channelled leaves and white flowers 3-4 mm long. It flowers from spring to summer.
   
• The var. coccinea is confined to the coast between Port Elizabeth and King William's Town. It is up to 1.5 m tall with spreading green leaves and red flowers up to 7 mm long (summer flowering).
   
• The var. heterotricha is up to 40 cm tall with erect grey-green leaves and white flowers up to 7 mm long. It flowers in winter and has a very wide distribution from tropical Africa to South Africa (to the northeast Eastern Cape). Var. heterotricha grows on the escarpment and below the escarpment mountains and in river valleys, often confined to ledges.