ERICACEAE, in botany, a family of plants belonging to the higher or sympetalous division of dicotyledons. They are mostly woody plants, with a slender creeping stem as in bilberry (blueberry), Vaccinium (fig. I), or forming low bushes as in the heaths, or sometimes becoming tree-like, as in species of Rhododendron. The leaves are alternate, opposite or whorled in arrangement, and in form and structure show well-marked adapta tion to life in dry or exposed situations. Thus in the true heaths they are needle-like, with the margins often rolled back to form a groove or an almost closed chamber on the under side. In others such as Rhododendron they are often leathery and ever green, the strongly cuticularized upper surface protecting a water storing tissue situated above the green layers of the leaf. The flowers are sometimes solitary and axillary or terminal as in Andromeda, but are generally ar ranged in racemose inflorescences at the end of the branches as in Rhododendron, or on small lat eral shoots as in Erica. They are hermaphrodite and generally reg ular with parts in 4's or 5's, thus : sepals 4 or 5, petals 4 or 5, sta mens 8 or i o in two series, the outer opposite the petals, and carpels 4 or 5. The corolla is usually more or less bell-shaped, and in the heaths persists in a dry state in the fruit. The petals with the stamens are situated on the outer edge of a honey-secreting disk. The anthers show great variety in shape, the halves being often more or less free and often appendaged; they open to allow the escape of the pollen by a terminal pore or slit. The carpels are united to form a 4- or 5-chambered ovary, which bears a simple elongated style ending in a capitate stigma; each ovary chamber contains one to many ovules attached to a central placenta. The brightly coloured corolla, the presence of nectar and the scent render the flowers attractive to insects, and the projection of the stigma beyond the anthers favours crossing. The fruit is generally a capsule con taining many seeds, as in Erica or Rhododendron (fig. 2) ; some times a berry, as in Arbutus.
The family falls into four distinct tribes, characterized by the relative position of the ovary and by the fruit and seed. They are : 1. Rhododendroideae, characterized by capsular fruit, seed with a loose coat, deciduous petals and anthers without appendages. It consists mainly of the large genus Rhododendron (in which Azalea is included), which is chiefly developed in the mountains of eastern Asia, many species occurring on the Himalayas. Dabeo cia, St. Dabeoc's heath, occurs in Ireland. In eastern America, Kalmia (laurel) is the prominent genus after Rhododendron.
2. Arbutoideae.—Fruit a berry or capsule, petals deciduous and anthers with bristle-like appendages, chiefly north temperate to arctic in distribution. Arbutus Unedo, the strawberry-tree, so called from its large scarlet berry, is southern European extending into south Ireland. Arctostaphylos (bearberry) and Andromeda are arctic and alpine genera occurring in Britain and also extending from the arctic into the mountainous regions of northern United States. Epigaea repens is the trailing arbutus or mayflower of Atlantic America.
3. Vaccinioideae.—Ovary inferior, fruit a berry. Extends from the north temperate zone to the mountains of the tropics. Vaccinium, the largest genus, has three British species : V. Myrtil lus is the bilberry (q.v.), blueberry or whortleberry, V. Vitis-Idaea the cowberry, and V. Oxycoccos the cranberry (q.v.). There are 20 species recognized in the United States.
4. Ericoideae.—Fruit usually a capsule, seeds round, not winged; corolla persisting round the ripe fruit ; anthers often appendaged. The largest genus is Erica, the true heath (q.v.), with Soo species, the majority confined to the Cape; others occur on the mountains of tropical Africa and in Europe and north Africa, especially the Mediterranean region. E. cinerea (purple heather) and E. Tetralix (cross-leaved heath) are common British heaths. Callum is the ling or Scotch heather. The genus is not represented in the United States.