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Major Groups, Families and Genera
Lamiaceae (Labiatae)
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What are the Lamiaceae
How many species does the family contain?The Lamiaceae is a family of flowering plants that comprises over 240 genera and 6,500 species worldwide.
Although occurring almost throughout the world, with the exception of the coldest polar regions, the Lamiaceae are particularly well represented in tropical and temperate areas especially those with a seasonal climate, such as the Mediterranean region and in tropical upland savannas. While some species are characteristic of semi-arid conditions, many others are adapted to wet habitats, in seasonally flooded areas or along river banks in forest. |
Plectranthus crassus |
Characteristics
Please select a relevant character of interest from the table:
Table of characters associated with Lamiaceae
Trees, shrubs or herbs |
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Usually square in cross section |
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Usually opposite, without stipules, decussate |
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Multicellular hairs usually present and are often diverse in form. |
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Many species (especially in subfamily Nepetoideae) are highly aromatic, being rich in essential oils. |
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Hermaphrodite, usually entomophilous, arranged in thyrsoid inflorescences, the cymes often extremely complex or reduced, and the flowers sometimes strongly congested, occasionally forming heads. |
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Usually with five lobes, tubular or funnel-shaped and often two-lipped, but can be extremely diverse in shape, especially in fruit. |
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Sympetalous, tubular often zygomorphic or occassionally actinomorphic. |
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Usually four didynamous (anterior pair longer). Anthers basifixed often with prominent connectives. Anther structure, and the shape of the connective can be diverse. |
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Often gynobasic, arising between the deeply four-lobed ovary, but is terminal in some groups, when the ovary may be entire or only shallowly lobed. |
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Superior and normally composed of two carpels (rarely more), each usually divided into two loculi, by the formation of a "false septum", and each containing a single ovule, although some variation from this can be found. |
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Often present below the ovary. |
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Normally consists of four mericarps (single seeded ), known as nutlets, but can sometimes be drupaceous or breaking up into 2 or 4 dry mericarps, which may be one- to two-seeded. |
What is the relationship with Verbenaceae?
The Verbenaceae
The Verbenaceae are trees, shrubs, lianes or herbs, often characterized with square stems and opposite leaves. The hairs on stems and leaves are usually unicellular (except in Stachytarpheta). Some species, such as Aloysia and Lippia, are noted for their essential oils. The flowers which are usually entomophilous (two-lipped with lobes spreading), are arranged in spikes, racemes or in heads derived from them (as in some Lippia and Lantana species). The calyx is usually four- to five-lobed and tubular, the corolla is tubular and somewhat zygomorphic, but not strongly two-lipped. There are four or two, rarely five, stamens included, often included within the corolla tube. The style is terminal, the ovary is entire and usually composed of four uni-ovulate, or two bi- or uni-ovulate loculi.The fruit is usually a dry schizocarp, breaking into four or two one- or two-seeded mericarps, at maturity, but some genera have drupaceous fruit.
The traditional division between Lamiaceae and Verbenceae
The traditional division of Lamiaceae and Verbenaceae (e.g. Bentham & Hooker 1876, Baker & Stapf 1900) is far from satisfactory. This delimitation was based on whether the taxa were mostly woody with a terminal or subterminal style (Verbenaceae) or mainly herbaceous with a gynobasic style (Lamiaceae). The limitations of this classification were pointed out by Junell (1934) and elaborated upon by Cantino (1992 a & b). The traditional classification is difficult to implement and does not represent phylogenetically natural taxa.
A new division
A new division of the families has been proposed which gives groups which are both easily communicable and monophyletic. The classification is outlined in Cantino (1992 a & b), Cantino, Harley & Wagstaff (1992) and Thorne (1992), and relationships are further explored in Wagstaff et al. 1997 & 1998. This classification is now being accepted and used in the most recent textbooks (e.g., Zomlefer 1994).
The Verbenaceae has been restricted to subfamily Verbenoideae, which has a racemose inflorescence and salverform (lobes spreading) corolla, whereas the inflorescence is cymose in the Lamiaceae and the corollas are tubular and usually bilabiate (two-lipped). These morphological differences are supported by embryological and pollen characters.
Useful references
Baker, J.G. & Stapf, O. (1900). Verbenaceae & Lamiaceae in Thistleton-Dyer, W.T., ed. Flora of Tropical Africa 5: 273502. London: Reeve & Co.
Bentham, G. & Hooker, J.D. Verbenaceae & Lamiaceae in Genera Plantarum 2: 11311223. London: Reeve & Co.
Cantino, P.D. (1992a). Evidence for a polyphyletic origin of the Lamiaceae. Ann. Missouri Bot. Gard. 79: 361379.
Cantino, P.D. (1992b). Toward a phylogenetic classification of the Labiate. In: Harley, R.M. & Reynolds, T. eds, Advances in Labiate Science: 2737. Kew: Royal Botanic Gardens.
Cantino, P.D., Harley, R.M. & Wagstaff, S.J. (1992). Genera of Lamiaceae: status and classification. In: Harley, R.M. & Reynolds, T. eds, Advances in Labiate Science: 511522. Kew: Royal Botanic Gardens.
Junell, S. (1934). Zur gynäceummorphologie und Systematik der Verbenaceen und Labiate. Symb. Bot. Upsal. 4: 1219.
Thorne, R.F. (1992). Classification & geography of the flowering plants. Bot. Rev. (Lancaster) 58: 225348.
Wagstaff, S.J. & Olmstead R.D. (1997). Phylogeny of Lamiaceae inferred from rbcL sequences. Syst. Bot. 22: 165-179 (1997).
Wagstaff, S.J., Hickerson, L., Spangler, R., Reeves, P.A. & Olmstead, R.D.(1998). Phylogeny in Lamiaceae s.l. inferred from cpDNA sequences. Pl. Syst. Evol. 209:265-274.
Zomlefer, W.B. (1994). Flowering Plant Families. Chapel Hill, North Carolina: University North Carolina Press.