The genus Calluna was formerly included in Erica – it differs in having even smaller scale-leaves (less than 2–3 millimetres long), and the flower corolla consisting of separate petals.

A number of increasingly detailed phylogenetic hypotheses for Erica have been published based on nuclear ribosomal and plastid DNA sequences.

[8][9][10][11] The closest relatives of Erica are Daboecia (one or two species) and Calluna (monospecific), representing the oldest surviving lineages of a, by inference, ancestrally Palearctic tribe Ericeae.

[9] The small number of European Erica species represent the oldest lineages of the genus, within which a single, order-of-magnitude more species-rich, African clade is nested.

[14] Around 690 of the species are endemic to South Africa, and these are often called the Cape heaths, forming the largest genus in the fynbos.

Plants of this genus are eaten mainly by the larvae of many Lepidoptera species, including Saturnia pavonia, garden tiger moth, true lover's knot, wormwood pug, the silver-studded blue,[17] and the Coleophora case-bearers C. juncicolella and C. pyrrhulipennella.