The below mentioned article provides an overview on Order Lamiales, Family–Lamiaceae . After reading article you will learn about: 1. Introduction to Order – Lamiales 2. Explanation on Family-Lamiaceae (Labiatae) 3. Economic Importance.
Contents
Introduction to Order – Lamiales:
According to Hutchinson this is the eighty-second order of the phylum Angiospermae, subphylum Dicotyledones and division Herbaceae. This order comprises of four families, e.g., Myoporaceae, Selaginaceae, Globulariaceae and Labiatae, of which the Labiatae has been described in this article in detail, Bentham and Hooker have placed the Labiatae along with three other families including Verbenaceae, in the tenth order the Lamiales of class Dicotyledones, division Gamopetalae and series Bicarpellatae.
Engler and Prantl have placed the Labiatae along with nineteen other families including Convolvulaceae, Verbenaceae, Solanaceae, Scrophulariaceae, Pedaliaceae, Acanthaceae, etc., in the sixth order the Tubiflorae of class Dicotyledoneae and sub class Sympetalae.
Leaves mostly opposite or whorled; corolla zygomorphic; stamens 4 or 2; ovary becoming lobed with a gynobasic style; ovules mostly paired. Largely herbaceous, with inflorescence tending to capitula or verticillasters.
Explanation on Family-Lamiaceae (Labiatae):
There are about 200 genera and 3200 species in this family.
Distribution:
The members of this family are found throughout the world. They are being distributed both in temperate and tropical regions. The chief centre of distribution of the family is the Mediterranean region. In our country the family is represented by several important genera, such as, Mentha, Ocimum, Leucas, Coleus, Pogostemon, etc.
Habit:
Majority of the plants are annual or perennial herbs, inhabiting the temperate regions. In warmer climates, the plants become shrubby in nature. Trees are rare. Certain plants are xerophytes with extremely reduced leaves. A few species are climbers, but the climbing habit is very rare.
Some important herbs are, Coleus aromaticus, C. forskohlii, Leucus cephalotes, Mentha arvensis, Ocimum sanctum, O. basilicum, etc., Salvia aegyptiaca, Coleus rotundifolius are undershrubs, Ocimum gratissimum, Meriandra bengalensis are shrubs. Certain species of Brazilian genus Hyptis and Indian genus Leucosceptrum are trees.
The certain species of Mentha and Lycopus are found in marshy places. A few American species of Scutellaria are climbers. Certain plants are extreme xerophytes, e.g., Rosmarinus. In this plant the leaves are rolled back and stomata are found among the hairs in the grooves on the underside of the leaf.
The propagation of many plants of this family takes place by means of new shoots which remain attached to the plant, e.g., in Salvia, Ballota. In Ajuga reptans the new shoots form aerial runners with somewhat reduced leaves; in Lycopus, the subterranean stolons (suckers) are found with short internodes and scaly colourless leaves. The suckers are found in the species of Mentha.
Stem:
The young shoots are usually four-sided or quadrangular.
Leaves:
Usually the leaves are simple, opposite, decussate and exstipulate. They show many variations from an entire blade to toothed, lobed, cut or finely dissected as in many species of Salvia. A whorled leaf arrangement of 3 to 8 leaves is found in some genera, e.g., Ocimum.
All parts of the plants, such as stem, leaves and inflorescence are more or less hairy and possess glandular hairs, which secrete characteristic scent of the genus or species. Sessile scented oil secreting glands are also found frequently on the epidermis.
Inflorescence:
The characteristic inflorescence of the family is verticillaster. In this type of inflorescence the whorls of flowers develop at the nodes. This consists of a pair of cymose inflorescences. Each cyme forms a simple three-flowered dichasium, e.g., in the species of Salvia, Prunella and others.
Sometimes, instead of a pair of simple dichasial cymes, the branching takes place and pair of monochasial cyme, develops, e.g., in Lamium, Ballota, Nepeta, etc.
In certain cases all axes are reduced developing a dense sessile inflorescence, k.g., in Leucas. In other cases the main axis or the lateral axes or both are more or less developed. In certain cases a number of whorls are aggregated together towards the top of the stem, and the subtending leaves being reduced to a bract-like structure.
Here, a raceme or spike like inflorescence is developed, e.g., in Prunella, Teucrium, etc. In Hyptis, Monarda and others the inflorescence becomes head-like. In the species of Scutellaria, Teucrium, etc., the flowers crowd towards one side of the main axis, developing into dorsiventral inflorescences. Very rarely the flowers are solitary axillary, e.g., in Scutellaria.
Flowers:
The plan of construction of the flowers is uniform. They are hermaphrodite, zygomorphic, rarely actinomorphic, e.g., in Mentha, Elshotzia, complete, hypogynous.
Calyx:
The calyx consists of five sepals, gamosepalous. The sepals are inferior, persistent, campanulate or tubular, with free teeth or lobes, sometimes bilabiate (two-lipped), e.g., in Thymus, Salvia, etc. In Orgianum, the calyx is two-lipped, in Hoslundia, the persistent sepals become fleshy in the fruit. The aestivation may be valvate, imbricate or rarely quincuncial.
Corolla:
It consists of five petals, gamopetalous, tubular and limb variously bilabiate. The corolla consists of two pairs, viz., tube and limb. The tube is straight or bent and wide towards the mouth. The limb is rarely equally fine toothed. In Mentha, two upper teeth become united forming an almost regular tetramerous corolla.
The arrangement of the upper and lower lip of the limb is as follows- In majority of cases 2/3 arrangement is found, here the posterior pair of petals forms the upper lip which may be flat, e.g., in Thymus, or concave, e.g., in Salvia, Stachys, etc.
In the species of Ocimum, Hyptis etc., 4/1 arrangement of the petals is found. In such cases four upper petals form a developed upper lip while the anterior petal forms the lower lip. The 0/5 arrangement of petals is found in Teucrium. Here all the lobes being pushed forward. The aestivation is imbricate.
Androecium:
The stamens are typically four, didynamous, sometimes reduced to two. They are epipetalous and alternate with the corolla lobes. The fifth posterior stamen is usually absent and rarely developed. In majority of cases it is completely suppressed but in certain cases it is represented by a staminode.
In Salvia, Lycopus, etc., the two upper stamens are very often represented by staminodes or altogether suppressed. In Coleus, the stamens are monadelphous. Usually the anterior pair of the stamens is longer than the posterior pair, but in Nepeta and other allied genera the posterior pair is longer than the anterior pair.
The anthers are two-celled; dehisce by longitudinal slits. In between the two cells of the anther, a connective is found. In Salvia this connective becomes filiform and articulated with the filament. In this case, the anterior cell of the anther is being reduced or sterile and modified. Generally a four-lobed hypogynous disc is present. The anterior lobes of the disc secrete nectar.
Gynoecium:
It consists of two median carpels, syncarpous, found to be seated on a hypogynous, nectar secreting disc. In very early stages, the ovary is two-celled (bilocular) but later on a constriction develops which divides the two carpels into four one-ovuled segments. The ovules are anatropous.
The ovules are attached at the inner comer of each ovary segment. The style is very characteristic of the family. It arises from the base of the ovary in between the four loculi, and is known as gynobasic style. The stigmatic papillae of bilobed stigma are situated at the tip of the style arms. The placentation is axile. The ovary is superior.
Fruit:
The fruit consists of four one-seeded nutlets, included within the persistent calyx.
Seeds:
Exalbuminous or with scanty endosperm. The testa is thin; the embryo possesses flat cotyledons.
Pollination:
The pollination takes place through the agency of insects (i.e., entomophilous).
Description of some important plants in semi-technical language:
1. Ocimum sanctum, (Verna.-Tuisi):
Habit:
A perennial herb with typical aromatic smell.
Stem:
Erect, branched, quadrangular, somewhat woody, solid, branches covered with soft hairs.
Leaf:
Simple, opposite, short petioled, exstipulate, ovate, serrate, acute, gland dotted, unicostate reticulate venation.
Inflorescence:
Verticillaster, 6-10 flowered whorls present, emitting fine smell.
Flower:
Pedicellate, bracteate, bracts small and caducous, hermaphrodite, zygomorphic, complete, purple, hypogynous.
Calyx:
5 sepals, gamosepalous, bilabiate, petaloid (purple coloured), posterior lip broad and boat shaped, anterior lip with 4 small lobes possessing mucronate teeth, gland dotted, imbricate aestivation, inferior.
Corolla:
5 petals, gamopetalous, bilabiate, corolla tube short, upper lip four lobed, lower lip large, imbricate aestivation, inferior.
Androecium:
4 stamens, polyandrous, didynamous, epipetalous, fifth posterior stamen completely suppressed, anthers bicelled, introrse, dorsifixed.
Gynoecium:
2 carpels (bicarpellary), syncarpous, ovary bilocular in early stage but becomes tetralocular in later stage, ovary superior, four chambered, axile placentation, single ovule in each loculus, gynobasic style (i.e., it arises from the base of the ovary), stigma bifid.
Fruit:
Schizocarpic, carcerulus, 4 nutlets developed.
2. Salvia officinale:
Habit:
An annual ornamental herb with typical aromatic smell.
Stem:
Erect, branched, herbaceous, quadrangular, solid, hairy and green.
Leaf:
Simple, opposite, decussate, petiolate, exstipulate, ovate, serrate, acute, unicostate reticulate venation.
Inflorescence:
Verticillaster with usually six-flowered whorls.
Flower:
Pedicellate, bracteate, hermaphrodite, zygomorphic, complete, coloured, hypogynous.
Calyx:
5 sepals, gamosepalous, bilabiate, 2 lobes consisting of one lip and three the other lip, petaloid, imbricate aestivation, inferior.
Corolla:
5 petals, gamopetalous bilabiate, 2 lobes in one whorl and 3 in the other, imbricate aestivation, inferior.
Androecium:
2 stamens (anterior), posterior, 3 stamens absent or staminodes present, epipetalous, short filament connected to a long connective, lower end of connective is flat, short and sterile, upper end of it with a large, fertile anther lobe, anthers bicelled, introrse.
Gynoecium:
2 carpels (bicarpellary), syncarpous pistil present on nectar secreting disc, ovary superior, bilocular when young, but becomes tetralocular in the later stage, single ovule in each loculus, axile placentation, gynobasic style, bifid stigma.
Fruit:
Four nutlets in a group.
Economic Importance of Family-Lamiaceae (Labiatae):
The family is of little economic value. Some plants are grown in the gardens as ornamentals; some plants yield essential oil while certain possess medicinal properties.
A list of few important plants is given below:
1. Coleus sp.; Several species of Coleus are grown as ornamentals in the gardens for their variously coloured beautiful foliage.
2. Coleus amboinicus; Syn. C. aromaticus; Eng.-Indian borage; Verna.-Pathorchur-This is a common herb. Its leaves are used for flavouring food products.
3. Coleus forskohlii, Syn. C. barbatus; This is a herb, cultivated in South India. The roots are used as spice and condiment.
4. Coleus rotundifolius; Eng.-Madagascar potato; Verna-Koorkan-This is a herb or shrub commonly grown in South India. The underground tuberous stems are eaten as vegetable.
5. Colebrookea oppositifolia; Verna.-Binda-The leaves are applied to wounds. The wood is used for making gun powder.
6. Leucas cephalotes; Verna.-Goma-This is a common herb. The flowers are used medicinally for cough and cold.
7. Leucas zeylanica; Verna.-Gattatumba-The fresh juice of leaves is used as a remedy for headache and cold. It is also applied to skin diseases. The flowers are used for cough and cold.
8. Meriandm bengalensis; Verna.-Kafur ka pat- This is a shrub grown as an ornamental. The leaves possess medicinal properties. They emit a camphor-like scent. The leaves are used to preserve clothes against insects.
9. Mentha arvensis; Eng.-Field mint; Verna.-Pudina-This is a perennial herb. The leaves yield an essential oil which is used in the manufacture of certain kinds of cigarettes and pharmaceuticals. It is also used as a carminative, stimulant and refrigerant. Usually grown in the Punjab, Western Himalayas, Kashmir and Kumaon hills.
10. Mentha arvensis var pipemscens; Eng.-Japanese peppermint. The leaves are the source of an essential oil, from which menthol is prepared. It is used in the treatment of colds. The plant is a herb and commonly cultivated in Jammu and Kashmir.
11. Mentha longifolia; Syn. M. sylvestris; Eng.-Mint; Verna.-Pudina-This is an aromatic herb. The leaves are used for flavouring purposes. The dried leaves are used as stimulant and carminative. Usually cultivated in Uttar Pradesh, Kashmir, Maharashtra and the Punjab.
12. Mentha piperita; Eng.-Peppermint; Verna.-Vilayati pudina-The leaves are used for flavouring purposes. An essential oil is obtained from the leaves, which is used in perfumery and soap making industries. The oil is also used medicinally as stimulant, carminative and for sickness and vomiting. This is a herb, cultivated in the Punjab, Kashmir and Maharashtra.
13. Mentha pulegium; Eng.-European pennyroyal-An essential oil is extracted from the leaves and tops of the plants, which is used in perfumery and cosmetics. It is herb, cultivated in Jammu and Kashmir.
14. Mentha spicata; Syn. M. viridis’, Eng.-Spearmint; Verna.-Pahari pudina-The leaves yield an essential oil, known as spearmint oil, which is used for flavouring food products. This herb is cultivated in the Punjab, Uttar Pradesh and Maharashtra.
15. Lavandula officinalis; Syn. L.vera; L. spica; Eng.-Lavender-This is a small shrub. It is native of Europe but now grown in Jammu and Kashmir. An essential oil is extracted from its flowers which is used in perfumery.
16. Ocimum sanctum; Eng.-Holy basil; Verna.-Tulsi-This is a small shrub and treated as holy plant by Hindus. Usually grown in the courtyards of Hindus and by the side of temples. This plant possesses several medicinal properties. The juice of the leaves is used as a stimulant and as a remedy for bronchitis. The seeds are used as a remedy for urino-genital troubles. The plant is used as an antidote for snake-bite.
17. Ocimum kilimandscharicum; Eng.-Camphor basil. The camphor is obtained from the leaves. It is cultivated on a very small scale in West Bengal, Assam, Tamil Nadu and Dehradun.
18. Ocimum basilicum; Eng.-Basil; Verna.-Bantulsi-This is an aromatic herb cultivated throughout our country. The leaves are used for flavouring purposes. The seeds are used medicinally as a remedy for dysentery and diarrhoea.
19. Ocimum gratissimum; Eng.-Shruby basil; Verna.-Ranitulsi-This is a common ornamental, aromatic shrub. The plant possesses medicinal properties. The seeds are given in headache. This is also used as a mosquito repellant.
20. Pogostemon perilloides-, Verna.-Pacholi-This is a herb. The leaves yield an essential oil, which is used for making soaps and perfumes. The dried leaves are used for scenting clothes to keep off insects. It is commonly cultivated in the Western Ghats and Nilgiris.
21. Rosmarinus officinalis; Verna.-Rusmori-This is a herb grown as an ornamental. It yields an essential oil which is used in perfumery.
22. Roylea calycina; Verna.-Patkarru-The plant possesses medicinal properties and used as a bitter tonic.
23. Salvia officinalis-, Eng.-Sage; Verna.-Salbia, Sefakuss, Seesti-This is a small shrub, grown as an ornamental. This is native of Mediterranean region.
24. Salvia splendens; Syn. S.colorans; Eng.-Scarlet sage-This is grown as an ornamental.
25. Satureja hortensis; This is a herb found in Kashmir. The aromatic stem and leaves are used for flavouring food products.
26. Anisomeles indica; Syn. A. ovata; Verna.- Gopali, Kalabhangra-This is a woody herb, found throughout our country used as fodder and for flavouring purposes.
Systematic Relationships:
Bentham and Hooker have included five families in the order Lamiales. They are Myoporineae, Selagineae, Verbenaceae, Labiatae and Plantagineae. Engler and Prantl have included (excluding Selagineae) in the order Tubiflorae. Hutchinson has included the families Myoporaceae, Selagineae, Globulariaceae and Labiatae in his order the Lamiales and the Verbenaceae in the Verbenales.
The Family Verbenaceae is related phylogenetically to the Labiatae. Bessey has also included these families within the Lamiales. Originally Hutchinson (1926) included the Verbenaceae in the Lamiales but later on (1948) he transferred the family Verbenaceae in the Verbenales. He considered that the Verbenaceae and Labiatae are quite unrelated and the Verbenaceae have been derived from Rubiaceae.