Lamiaceae

Abstract

Lamiaceae, or Labiatae, also known as the mint or dead nettle family, in the order of Lamiales, is a family of dicotyledonous flowering plants, with worldwide distribution, mostly in the Mediterranean regions and Southwest Asia. The enlarged Lamiaceae contains about 236 genera and has been stated to contain 6900 to 7200 species, but the world checklist lists 7534. Plants are usually herbs, subshrubs, or shrubs; aromatic; simple hairy, articulate hairy or glandular hairy; rarely stellate hairy, and often dispersed glandular spots. Stems are erect, obliquely ascending or procumbent, 4-edged with branches or branchlets, and longitudinally grooved. Leaves are usually simple, undivided to pinnately partite, rarely pinnately compound, opposite or whorled, rarely alternate, and petiolate. Stipules are absent. Cymes are with numerous flowers to reduced or only solitary, forming verticillaster in nodes or cymes or verticillasters further composed of terminal or axillary racemose, spicate, capitate, or coniform compound. Bracts are leaflike below, gradually smaller upward, bractlet-like, or totally bractlet-like. There is one pair of small bracts below every flower. Flowers are bisexual, rarely unisexual, zygomorphic, and rarely actinomorphic. Calyx is connate at base to campanulate, tubular or urceolate, apex 5-lobed, rarely 3- or 2- or 10-lobed. Lobes are usually unequal, 2-lipped, and rarely 1-lipped or nearly equal. Corolla is white, yellow, red, purple, or bluish purple, connate to tubular or campanulate, limbs 5- or 4-lobed, usually 2-lipped, and rarely single lip or false single lip, or nearly actinomorphic. Stamens are four, didynamous, rarely reduced to two stamens, and inserted on corolla tube. Anthers are 2-loculed, longitudinally indehiscent, rarely 1-loculed after anthesis, or reduced to 1-loculed, forming semi-anther, sometimes connective, much exserted, connate to filaments, with articulator at junction position. Disk is fleshy, entire or 2–4-lobed, sometimes anterior lobe, and posterior one digitally inflated. Carpels are two, 2-partite, and rarely undivided. Ovary is superior, parted to 4-loculed, axile placenta. There is one ovule per locule. Styles are solitary, inserted on bottom of ovary and rarely above ovary bottom. Stigma is usually bifid. Fruit is usually four dry nutlets and rarely drupe-like. Seeds are without endosperm or very poorly. Twenty four species, belonging to 17 different genera, are illustrated in the chapter.