Many species have five petals, often grown together. Fusion of the petals as a trait was traditionally used to place the order in the subclass Sympetalae.[2]
Mycorrhizal associations are quite common among the order representatives, and three kinds of mycorrhiza are found exclusively among Ericales (namely, ericoid, arbutoid and monotropoid mycorrhiza). In addition, some families among the order are notable for their exceptional ability to accumulate aluminum.[3]
Ericales are a cosmopolitan order. Areas of distribution of families vary largely – while some are restricted to tropics, others exist mainly in Arctic or temperate regions. The entire order contains over 8,000 species, of which the Ericaceae account for 2,000–4,000 species (by various estimates).
These make up an early diverging group of asterids.[6] Under the Cronquist system, the Ericales included a smaller group of plants, which were placed among the Dilleniidae:
^Robyns, W. (31 December 1972). "Outline of a New System of Orders and Families of Sympetalae". Bulletin du Jardin Botanique National de Belgique. 42 (4): 363–372. doi:10.2307/3667661. JSTOR3667661.
^Bremer, Birgitta; Kåre Bremera; Nahid Heidaria; Per Erixona; Richard G. Olmsteadb; Arne A. Anderbergc; Mari Källersjöd; Edit Barkhordarian (August 2002). "Phylogenetics of asterids based on 3 coding and 3 non-coding chloroplast DNA markers and the utility of non-coding DNA at higher taxonomic levels". Molecular Phylogenetics and Evolution. 24 (2): 274–301. doi:10.1016/S1055-7903(02)00240-3. PMID12144762.
du Mortier, B.C.J. (1829). Analyse des Familles de Plantes : avec l'indication des principaux genres qui s'y rattachent. Vol. 28. Tournay: Imprimerie de J. Casterman.
Smets, E.; Pyck, N. (February 2003). "Ericales (Rhododendron)". Nature Encyclopedia of Life Sciences. Nature Publishing Group. Archived from the original on 13 May 2011. Retrieved 23 March 2022.
Arne A. Anderberg; Bertil Stahl; Mari Kallersjo (May 2000). "Maesaceae, a New Primuloid Family in the Order Ericales s.l.". Taxon. 49 (2): 183–187. doi:10.2307/1223834. JSTOR1223834.
