What is the Lamiales plant order?

The Lamiales order, also known as the mint order, is a group of flowering plants with approximately 23,755 species, distributed among 24 families. Lamiaceae (mint) and Verbenaceae (verbena) are the two main families. Key traits of the Lamiales order: * Leaves are opposite. * Flowers are bilaterally symmetrical. * They have two or four stamens. Many members of the mint family (Lamiaceae) are aromatic and cultivated for their essential oils, which are used in medicine, flavoring, and perfumery. Culinary herbs like oregano , basil , sage , rosemary , and thyme belong to this family.

Where are Lamiales plants usually found?

Lamiales is a large order of flowering plants with about 23,755 species across 24 families. The two core families of Lamiales are Lamiaceae , or the mint family, and Verbenaceae , or the verbena family. One family within Lamiales, Pedaliaceae , is native to the Old World in tropical and dry habitats. Byblidaceae is native to Australia and New Guinea. Lentibulariaceae are herbs of wet habitats.

What are some common features of Lamiales plants?

Lamiales, an order of flowering plants, contains 24 families, 1,059 genera, and about 23,755 species. Technical and molecular characteristics that are common throughout its families include the storage of carbohydrates as oligosaccharides instead of starch, specialized stomata in leaves, and the production of oxygenated flavones and other unique chemical compounds. More easily recognizable features of Lamiales include opposite leaves, frequent glandular hairs, and mostly capsular fruits. Many members of the order have bilaterally symmetrical flowers, with fewer stamens than petals. In many species, the corolla has two lips, and the base of the corolla may have a backward-projecting spur, which is the site of nectar production. The two core families of Lamiales are Lamiaceae , or the mint family, and Verbenaceae , or the verbena family.

What is the importance of Lamiales plants to humans?

The Lamiales order, containing around 23,755 species across 24 families, significantly impacts humans. The Lamiaceae, or mint family, within Lamiales, provides many culinary herbs such as oregano , basil , sage , thyme , and rosemary . Many members of the mint family are aromatic and cultivated for their essential oils, which are used medicinally, for flavoring foods and beverages, and in perfumery. Additionally, timber plants such as teak and Gmelina arborea (an Old World species) belong to the Lamiales order and are cultivated for timber and firewood.

How do scientists classify different families within the Lamiales order?

Scientists classify families within the Lamiales order based on a combination of morphological, technical, and molecular characters. The Angiosperm Phylogeny Group IV (APG IV) botanical classification system significantly expanded the Lamiales order, supported by shared traits such as storing carbohydrates as oligosaccharides instead of starch, specialized stomata in leaves, and the production of oxygenated flavones and unique chemical compounds. Key characteristics for classification include opposite leaves , glandular hairs, and capsular fruits. Many species have bilaterally symmetrical flowers with fewer stamens than petals. The androecium (stamens) can be dimerous, tetramerous, or pentamerous, influencing the shape and structure of the corolla. Ovary structure and placentation types (axile, parietal, or free-central) are also important. Molecular studies have reorganized families, such as Scrophulariaceae, based on common ancestry, leading to new placements in families like Plantaginaceae .

Lamiales

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Close-up of sage plant (Salvia officinalis) with elongated, soft, gray-green leaves growing densely on woody stems.

Lamiales

plant order

Also known as: mint order

Written by

Paul E. Berry

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Britannica Editors

History

Order characteristics

snapdragonCommon snapdragon (*Antirrhinum majus*).

While the order is significantly more heterogeneous than it was under the Cronquist classification system, the expanded Lamiales of the APG IV system is supported by a substantial number of technical and molecular characters that are common throughout its families. For instance, carbohydrates are stored as oligosaccharides and not as starch, leaves have specialized stomata, and plants often produce oxygenated flavones and other unique chemical compounds. More easily recognizable characters include usually opposite leaves, frequent presence of glandular hairs, and mostly capsular fruits.

toadflaxCommon toadflax (*Linaria vulgaris*).

Many members of the order have bilaterally symmetric flowers (irregularly shaped corollas with only one plane of symmetry), with fewer stamens than petals. In many species the corolla has two lips, the upper lip being composed of two petals and the lower of three. The number of petals in each lip is sometimes not obvious. Lips may be the same size, or one may be markedly larger. An upward bulge, the palate, in the central portion of the lower lip is pronounced in some species, such as common snapdragon (Antirrhinum majus), in which it closes the corolla throat. The base of the corolla may bear a backwardly projecting spur, as in Kenilworth ivy (Cymbalaria muralis), toadflax (Linaria), bladderworts (Lentibularia), and butterworts (Pinguicula); this spur is the site of nectar production.

winter jasmineWinter jasmine (*Jasminum nudiflorum*).

In some families of the order, the androecium (stamens) is constructed on a two-part (dimerous) or a four-part (tetramerous) plan, both of which are associated with regular corollas. For example, species of Oleaceae (e.g., ashes, forsythias, jasmine, and lilacs) typically have two stamens, and species of Buddleja (butterfly bush; a member of Scrophulariaceae) typically have four. In other families of the order, the androecium is constructed on a five-part (pentamerous) plan, associated mostly with corollas that are irregular. In these species departures from a full set of five stamens derive clearly from the suppression of one or more of the five. Thus, a few members of the order have five stamens (as in the mulleins; members of Scrophulariaceae), but most have only two or four. Species with four stamens (an upper pair and a lower pair) lack only the uppermost stamen. Other species lack the uppermost stamen and either the upper or the lower pair, leaving only two stamens. Any of the lost stamens may be represented by a staminode, or sterile stamen, borne in place of a normal stamen but not producing pollen. Depending on the species, a staminode may range from a minute projection on the inner surface of the corolla to an elongated filament-like structure equal in size and conspicuousness to the normal stamens (e.g., penstemon). In most species of the order, the stamen filaments are united with the petals (epipetaly), the degree of union ranging from slight to considerably more than half the length of the stamen. The stamens are alternate with the lobes of the corolla; that is, they are attached between the petals. In some highly irregular flowers, the alternate arrangement is difficult to see. The anthers of all members of the order have four pollen sacs. Pollen form and structure are exceedingly diverse. One family of the order, Acanthaceae, shows a wider range of pollen morphological features than almost any other family of flowering plants.

Venus's-flytrap. Venus's-flytrap (Dionaea muscipula) one of the best known of the meat-eating plants. Carnivorous plant, Venus flytrap, Venus fly trap

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Most species in the order have an ovary with two locules, or chambers, each representing a single carpel. Most families in the order have axile placentation (the ovules, or placentae, develop on a central column in the ovary), although some, such as Orobanchaceae and Gesneriaceae, have parietal placentation (the ovules are positioned along the outer walls of the ovary or along partial partitions extending inward). Lentibulariaceae is characterized by free-central placentation, in which the ovules are borne on a central stalk that arises from the base of the single locule.

Although most species of Lamiales produce several to many seeds per fruit, a few produce only one (ashes, some species of Globularia). Perhaps the record for seed production in the order goes to a member of Orobanchaceae, Boschniakia rossica, a small parasitic plant that produces more than 300,000 seeds. The size of seeds in Lamiales ranges from the dustlike seeds of broomrapes (Orobanchaceae), which can be less than 0.3 mm (0.01 inch) long, to the long, thin seeds of some members of Bignoniaceae, which can have a length of several centimetres.

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Lamiales

Order characteristics

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