Origin: Native

Notes: FNA8: "The closest relatives of the broadly defined Ericaceae are Clethraceae and Cyrillaceae. Some phylogenies show Cyrillaceae as sister to Ericaceae; other analyses have Clethraceae and Cyrillaceae as closest relatives to each other, together forming the sister group to Ericaceae. Monotropa and related genera (genera 5-12 of this treatment), and Pyrola and related genera (genera 1-4 of this treatment) have been treated as families Monotropaceae and Pyrolaceae. Not all botanists agreed with this, as summarized by G. H. M. Lawrence (1951): "Many botanists (including Hutchinson) have held the view that the Pyrolaceae are not sufficiently distinct from the Ericaceae to be treated as a separate family." Differences in habit, floral features, and pollen have helped maintain family status for Pyrolaceae and Monotropaceae in regional floras. Molecular and morphological analyses (K. A. Kron et al. 2002) show these lineages embedded within Ericaceae. Similarly, Empetraceae has been demonstrated to be nested within Ericaceae and is here included in the Ericaceae.

Studies in the last several decades, especially since 1990 including molecular data, have resulted in rearrangements of generic limits in the Ericaceae. These are discussed under the various genera; for the reader's convenience they are summarized here. Ledum is included in Rhododendron; Leiophyllum and Loiseleuria are included in Kalmia; and Hypopitys is included in Monotropa. Arctous is separated from the much larger Arctostaphylos, to which it is inferred to form a sister clade. Eubotrys is segregated from Leucothoe, with which it has often been combined. Vaccinium is treated in a broad sense, to include segregates such as Oxycoccus; although Vaccinium is decidedly polymorphic, this seems a workable approach until generic limits in the Vaccinieae Reichenbach are better understood."

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