Ericaceae, the heath family or the heather family is a plant family, comprising mostly calcifuge (lime-hating) plants that thrive in acidic soils. Many well-known plants of the Ericaceae live in temperate climates, such as cranberry, blueberry, various heaths and heathers (Erica, Cassiope, Daboecia, Calluna vulgaris etc), huckleberry, azalea and rhododendron. However, the family also contains many tropical species.
The Ericaceae consists of herbs, dwarf shrubs, shrubs and trees with leaves that are usually alternate or whorled, simple and without stipules, and hermaphrodite flowers. The flowers show considerable variability. The petals are often fused (sympetalous) with shapes ranging from narrowly tubular to funnelform or widely bowl-shaped. The corollas are usually radially symmetrical (actinomorphic) but many flowers of the genus Rhododendron are somewhat bilaterally symmetrical (zygomorphic).
Recent genetic research by the Angiosperm Phylogeny Group has resulted in the inclusion of the formerly recognised families Empetraceae, Epacridaceae, Monotropaceae, Prionotaceae and Pyrolaceae into Ericaceae. Most Ericaceae (except Monotropaceae, Prionotaceae and Pyrolaceae) form mycorrhizae, where fungi grow in and around the roots and provide the plant with nutrients. This symbiotic relationship is considered crucial to the success of members of the family in edaphically stressful environments worldwide. The Pyroleae tribe are mixotrophic and gain sugars from the mycorrhizae as well as nutrients.
Mountain laurel (Kalmia latifolia), showing radially symmetrical flower.
Rhododendron x campylocarpum flower showing bilateral symmetry.
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