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ERICACEAE
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ERICACEAE , in See also:botany, a natural See also:order of See also:plants belonging to the higher or gamopetalous See also:division of See also:Dicotyledons. They are woody plants, sometimes with a slender creeping See also:stem as in See also:bilberry, Vaccinium (fig. 1), or See also:Andromeda (fig. 2), or See also:form- See also:ing See also:low bushes as in the heaths, or larger, sometimes becoming See also:tree-like, as in See also:species of See also:Rhododendron. The leaves are alter- nate, opposite or whorled in arrange- ment, and in their form and structure show well - marked See also:adaptation for See also:life in dry or exposed situations. Thus in the true. heaths they are See also:needle-like, with the margins often rolled back to form a groove or an almost closed chamber on the under See also:side. In others such as Rhodo- dendron or Arbutus they are often leathery and ever- See also:green, the strongly cuticularized upper See also:surface protecting a See also:water-storing See also:tissue situated above the green layers of the See also:leaf. The See also:flowers are sometimes solitary and axillary or terminal as in Andromeda, but are generally arranged in racemose inflorescences at the end of the branches as in Arbutus and Rhododendron, or on small lateral shoots as in Erica. They are hermaphrodite and generally See also:regular with parts in 4 or 5, thus: sepals 4 or 5, petals 4 or. 5, stamens 8 or io in two See also:series, the See also:outer of which is opposite the petals, and carpels 4 or 5. The corolla is usually more or less See also:bell-shaped, and in the heaths persists in a dry See also:state in the See also:fruit. The petals with the stamens are situated on the outer edge of a See also:honey-secreting disk. The anthers show a very See also:great variety in shape, the halves are often more or less See also:free and often appendaged; they open to allow the See also:escape of the See also:pollen by a terminal See also:pore or slit. The carpels are See also:united to form a 4- to 5-chambered ovary, which bears a See also:simple elongated See also:style ending in a capitate stigma; each ovary-chamber contains one to many ovules attached to a central See also:placenta. The brightly coloured 1, Flowering shoot of Erica cinerea, about 12 nat. See also:size. 2, See also:Flower cut lengthwise. 5, 3, Stamen showing appendages and porous dehiscence of anther. 4, See also:Capsule showing the loculicidal dehiscence ; a few seeds re- corolla, the presence of See also:nectar and the See also:scent render the flowers attractive to See also:insects, and the See also:projection of the stigma beyond the anthers favours See also:crossing. The fruit is generally a capsule containing many seeds, as in Erica (fig. 3) or Rhododendron; some-times a See also:berry as in Arbutus. The order falls into four distinct tribes, which are characterized by the relative position of the ovary and by the fruit and See also:seed. They are as follows: 1. Rhododendron tribe, characterized by capsular fruit, seed with a loose coat, See also:deciduous petals and anthers without append-ages. It consists mainly of the great genus Rhododendron (in which See also:Azalea is included by See also:recent botanists), which is chiefly See also:main attached to the central See also:axis. See also:Diagram of the flower having four sepals, four divisions of the corolla, eight stamens in two rows, and four divisions of the See also:pistil. See also:developed in the mountains of eastern See also:Asia, many species occur-See also:ring on the Himalayas. Dabeocia, St Dabeoc's See also:heath, occurs in See also:Ireland. 2. Arbutus Tribe.—Fruit a berry or capsule, petals deciduous and anthers with bristle-like appendages, chiefly See also:north temperate to See also:arctic in See also:distribution. Arbutus Unedo, the See also:strawberry-tree, so called from its large See also:scarlet berry, is a See also:southern See also:European species which extends into See also:south Ireland. Arctostaphylos (bearberry) and Andromeda are arctic and alpine genera occurring in See also:Britain. Epigaea re pens is the trailing arbutus or See also:mayflower of See also:Atlantic See also:America. 3. Vaccinium Tribe.—Ovary inferior, fruit a berry. Extends from the north temperate See also:zone to the mountains of the tropics. Vaccinium, the largest genus, has four See also:British species: V. Myrtillus is the bilberry (q.v.), blaeberry or whortleberry, V. Vitis-Idaea the cowberry, and V. Oxycoccos the See also:cranberry (q.v.). This tribe is sometimes regarded as a See also:separate order Vacciniaceae, distinguished by its inferior ovary. 4. Erica Tribe.—Fruit usually a. capsule, seeds See also:round, not winged; corolla persisting round the ripe fruit; anthers often appendaged. The largest genus is Erica, the true heath (q.v.), with over 400 species, the great See also:majority of which are confined to the Cape; others occur on the mountains of tropical See also:Africa and in See also:Europe and North Africa, especially the Mediterranean region. E. cinerea (See also:purple heather) and E. Tetralix (See also:cross-leaved heath) are See also:common British heaths. Calluna is the See also:ling or Scotch heather. Additional information and CommentsThere are no comments yet for this article.
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