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The below mentioned article provides an overview on Family – Rubiaceae. After reading this article you will learn about: 1. Explanation on Family – Rubiaceae 2. Economic Importance of Family – Rubiaceae.
Explanation on Family – Rubiaceae:
There are about 400 genera and 5,300 species in this family.
Distribution:
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The family is cosmopolitan in distribution but the great majority of the species are found in tropical regions. The species of Galium, Oldenlandia, etc., are frequently found in the temperate regions. Certain species of Galium are found even in the Arctic zone or high elevations on tropical mountain ranges.
The species of Nertera are found to be spread along the Andes. The genus Comprosma is commonly found in the south temperate and Antarctic regions, Guettarda speciosa is quite common round the Indian Ocean from Africa to Malacca. The family is represented by several genera in our country, e.g., Cinchona, Coffea, Adina, Hamelia, Ixora, Galium, Gardenia, Mussaenda, Rubia, Morinda and many others.
Habit:
The plants show great variations in habit. Majority of plants are either trees or shrubs. The herbaceous plants are also common and mainly they are confined to certain tribes. The members of the tribe Galieae are exclusively herbaceous. The tendency towards the formation of herbaceous forms is widespread, as certain herbaceous genera, such as, Bouvardia sp., is found in the typically woody tribe Cinchoneke.
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The climbing habit is also found in the family. Some climbers are herbaceous, whereas certain others are shrubby twiners, e.g., Manettia. Uncaria is a typical example of hook climbers. However, Galium aparine possesses stiff recurving hairs, which help in climbing on the supporting vegetation.
The epiphytes also occur, e.g., Myrmecodia. Myrmecodia possesses a tuber-like stem developed from the swollen hypocotyl. This tuber-like stem contains a number of communicating galleries which harbour the ants. Such types of plants are known as myrmecophilous but the exact relation of ants to plant is not clear.
In the species of Nauclea, Duroia, etc., the ants live just beneath the inflorescence in the swollen hollow internodes. It is thought that the ants protect the flowers from other harmful insects. In the species of Remijia and Duroia, the ants live in the flask-shaped swellings situated on the leaf base.
Some important trees of the family are, Anthocephalus cadamba (Verna- Kadam), Adina cordifolia (Verna-Haldu), the species of Cinchona, Mitragyna parviflora, etc., Coffea arabica, Hamelia patens, many species oilxora. Gardenia, Mussaenda, etc., are medium sized or large shrubs. Certain species of Galium, Rubia, Oldenlandia, etc., are beautiful herbs.
Leaves:
They are simple, stipulate, opposite decussate, entire or rarely toothed.
The stipules may be inter or intra-petiolar. In the former case, the stipules are situated at the side of leaf-base and thus lie in between the leaves; whereas in the latter case the stipules are situated in front of the leaf base in between the petiole and the stem. Sometimes the stipules unite to each other and then to the petiole, forming a sheath like structure around the stem.
In certain species of the genus Gardenia, the stipules form a conical cap like structure which protects the apex of the stem, and is thrown off as the bud develops. Sometimes the stipules split into bristle like structures, and at the top of each bristle a resin secreting gland develops, e.g., in Pentas.
In the case of the stipules of Coffea, Gardenia, etc., such glands are situated at the base of the stipules In the case of Galium and allied genera, the leaf like (foliaceous) stipules are found. In such cases the stem apparently bears the whorls of leaves at the nodes, and the leaves may only be distinguished from the stipules by the presence of axillary buds.
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Inflorescence:
Usually the inflorescence is of cymose type, i.e., a dichasial or a panicled cyme. Sometimes the small-flowered dichasia are aggregated into dense globose heads. In these heads the inferior ovaries of the flowers unite together, e.g., in Sarcocephalus, Morinda, etc. In Gardenia, Randia, and some other plants the inflorescence consists of solitary terminal flowers.
In Coffea arabica the flowers are found to be arranged in axillary cymes, whereas in Ixora subsessilis, they are arranged in subsessile corymbose cymes.
The flowers of Oldenlandia are being arranged in panicled cymes. In Anthocephalus indicus and Adina cordifolia the flowers are found to be arranged in globose heads. In the species of Australian Pamax, the two flowers of a pair are so united, that the two possess a common calyx.
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Flowers:
The flowers are hermaphrodite, usually actinom-orphic and either tetramerous or pentamerous, with five or four stamens and two carpels. They are complete and epigynous. Sometimes the flowers become unisexual by means of reduction, e.g., Coprosma. The flowers of Henriquezia, are however zygomorphic.
Calyx:
The calyx consists of five or four sepals, gamosepalous. In the case of Mussaenda, Warscewiezia, etc., one or rarely more of the sepals become leaf like and white, yellow or variously coloured. The development of such leaf like sepal increases the attractiveness of the inflorescence and attraction for the insects.
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In certain cases the sepals increase in size only after fertilization e.g., Nematostylis, Alberta, etc. The aestivation is valvate.
Corolla:
The corolla consists of five or four petals, gamopetalous. The corolla is tubular, campanulate or rotate. In Henriquezia, the corolla is more or less zygomorphic and bilabiate. The aestivation is either contorted or valvate.
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Androecium:
It consists of five or four stamens. The stamens are epipetalous, i.e., they are inserted at or near the throat of the corolla tube. The stamens alternate with the petals. The anthers are bicelled, introrse and dehisce by longitudinal slits and sometimes by apical pores. In irregular corollas, the stamens are of unequal length and bent. In Oldenlandia, heteroandry occurs (i.e., the stamens are of different length).
Gynoecium:
Usually the gynoecium consists of two carpels, syncarpous. Generally the ovary is inferior, but in the Australian genus Synaptantha, it is half inferior. However, in Gaertnera and Pogamea, the ovary is superior. Generally the ovary is bilocular, but in Gardenia, it is unilocular, with parietal placentation.
In general, the placentation is axile. One to many ovules are found in each locule of the ovary. The style is simple with globose stigma.
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Fruit:
The fruit is a drupe, capsule or berry. They may be dry or fleshy. It is a fleshy berry e.g., in the case of Randia, Mussaenda, etc., it is a drupe, e.g., in Coffea and others; it is a capsule, e.g., in Silvianthus, Ophiorrhiza, etc. The fruits of the species of Galium are sticky, because of the presence of small stiff recurving hairs.
Seeds:
Generally the seeds are small and more or less winged, endospermic; the flat cotyledons of embryo lie face to face.
Pollination:
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The pollination is usually effected by means of insects (i.e., entomophily). The nectar, the flag-like sepals attract the insects.
Description of important plants in semi-technical language:
1. Ixora coccinea Linn; Verna. Rangan, Rookmini; Eng. Jungle flame Ixora:
Habit:
A large cultivated ornamental shrub.
Stem:
Erect, branched, solid, cylindrical, green, herbaeous or somewhat woody.
Leaves:
Cauline and ramal, simple, opposite, sessile, stipulate, ovate, smooth entire, acute, unicostate reticulate venation.
Inflorescence:
Cymose, corymbose cyme.
Flower:
Bisexual, actinom- orphic, pedicellate, bracteate, bracteolate, complete, epigynous, tetramerous.
Calyx:
4 sepals, gamosepalous, superior, valvate aestivation.
Corolla:
4 petals, gamopetalous, corolla tubular, twisted aestivation.
Androecium:
4 stamens, epipetalous, inserted at the mouth of corolla, polyandrous, sessile, anthers bicelled, introrse, dorsifixed.
Gynoecium:
2 carpels (bicarpellary), syncarpous, ovary inferior, bilocular, single ovule in each loculus, axile placentation, style very long, stigma single, bifid.
Fruit:
Berry.
2. Hamelia patens:
Habit:
A large, cultivated, ornamental, evergreen shrub.
Stem:
Erect, branched, cylindrical, hairy, solid, woody.
Leaves:
Simple, whorled (three or more leaves at each node), cauline, petiolate, stipulate, stipules interpetiolar, ovate, entire acute, unicostate reticulate venation.
Inflorescence:
Cymose, polychasial cyme, each branch helicoid.
Flowers:
Subsessile, ebracteate, bisexual, actinomorphic, complete, orange coloured, epigynous.
Economic value:
Grown as a hedge plant.
Calyx:
5 sepals, gamosepalous, petaloid, reddish, adnate to the ovary wall, superior valvate aestivation.
Corolla:
5 petals, gamopetalous, tubular, orange coloured, superior, twisted aestivation.
Androecium:
5 stamens, polyandrous, alternate to the petals, filaments short, epipetalous anthers basifixed, long, bicelled, introrse.
Economic value:
The plant is grown in gardens as an ornamental.
Gynoecium:
5 carpels (pentacarpellary), syncarpous, ovary infenior, pentalocular, several ovules in each loculus, axile placentation.
Fruit:
Berry.
3. Oldenlandia corymbosa:
Oldenlandia corymbosa L., Eng. Daman-paper. Root-simple, tap. Stem-herbaceous aeria, prostrate, branched, solid, angular, and green. Leaf-cauline and ramal, opposite decussate stipulate, interpetiolar stipules, simple, sessile, lanceolate, entire, acute, pubescent, unicostate reticulate. Inflorescence-cymose, axillary dichasial cyme.
Flower-Bracteate, bracteolate pedicellate, actmomorphic, hermaphrodite, complete, tetramerous, epigynous, cyclic. Calyx-4, gamosepalous, valvate, persistent. Corolla-4, gamopetalous, valvate, violet.
Androecium-4, polyandrous, epipetalous, filaments short, dithecous, basifixed introrse. Gynoecium-2, bicarpellaiy, syncarpous, inferior, bilocular, many ovules in each locule, axile, style short, stigma simple and globular.
Fruit-berry.
Economic Importance of Family – Rubiaceae:
From the point of view of its economic importance, the family is of great value.
A list of few important plants is given below:
1. Cinchona calisaya; Eng.-Quinine; Verna.-Cinchona-This is a tree. The famous medicine of malaria known as quinine is obtained from the bark of this tree. The tree is native of South America, but found in the Nilgiris and Sikkim.
2. Cinchona ledgeriana; The medicine known as ‘quinine’ which is used for malarial fevers is also extracted from the bark of the tree. This is grown in Bengal, the Khasia hills and South India.
3. Cinchona succirubra; The ‘quinine’ is also extracted from the bark of this tree. The medicine is used for the treatment of malarial fevers. It is grown in South India, Sikkim and Madhya Pradesh.
4. Cinchona officinalis; The tree yields ‘quinine’ used for malarial fevers. It is grown in South India and Ootacamund.
5. Coffea Arabica; Eng-Arabian coffee; Verna-Kafi-This is a large shrub. The famous non-alcoholic beverage “coffee” is obtained from its seeds. This is a native of Abyssinia, but now cultivated in the Nilgiris, Karanataka, Coorg and Travancore.
6. Coffea liberica; Eng-Liberian coffee-A non-alcoholic beverage is obtained from its seeds. The bush is native of West coast of Africa, but now also cultivated in Karnataka and Travancore.
7. Coffea robusta: Eng-Congo coffee-This is also a source of commercial coffee. It is native of Congo but now grown in Travancore, Karnataka and Tamil Nadu.
8. Adina cordifolia; Eng-Saffron teak; Verna-Haldu-This is a beautiful shade giving tree. The wood is used for carvings, construction work, flooring and for railway carriages. The plant possesses antiseptic properties.
9. Anthocephalus indicus; Syn. A. cadamba’, Eng-Kadam; Verna-Kadamba-This is a tree grown as an ornamental for its golden coloured flowers. The fruits are edible. The bark is used as a tonic. It is also given as antidote in snake-bite.
10. Hamelia patens; This is beautiful shrub with red flowers, grown in the gardens as an ornamental. The fruits are edible. The syrup of berries is given in dysentery.
11. Hymeodictyon excelsum; Verna-Bhaulan-This is a large tree. The bark is used in tanning. Match splints, tea boxes and packing cases are made from its wood. The leaves are used as fodder.
12. Ixora arborea; Syn. Ixora parviflom- Eng-Torch tree; Verna-Jilpai-This is a small tree. The torches are made from its branches.
13. Ixora chinensis; Eng-Chinese Ixora-This is a beautiful small shrub grown in the gardens as an ornamental.
14. Ixora coccinea; Eng-Jungle flame Ixora; Verna-Rangan-This is a shrub, grown as an ornamental. This is a good hedge plant.
15. Ixora fulgens-This is a shrub grown as an ornamental.
16. Ixora lutea-k shrub, grown as an ornamental.
17. Ixora nudulata-A shrub, grown as an ornamental for its white fragrant flowers.
18. Galium sp. -The plants are very ornamental, and grown in the gardens.
19. Gardenia campanulata; Verna-Bitmara-A large shrub. The leaves and fruits are edible. The plants are found in Assam and Bihar.
20. Gardenia gummifera; Eng-Gummy cape jasmine; Verna-Dikamli-The plant yields a gum-resin. It is used as carminative and stimulant, and also given in dyspepsia. The fruits are edible.
21. Gardenia jasminoides; Verna-Gandharaj-This is an ornamental shrub grown in the gardens. A yellow dye is obtained from the pulp of its fruits. An essential oil is extracted from its flowers, which is used in making of perfumes.
22. Gardenia latifolia; Verna-Papra-This is a small tree, usually grown as hedge plant.
23. Gardenia resinifera; Verna-Dikamli-This is a large ornamental shrub with fragrant flowers.
24. Mussaenda glabrata; Verna-Bedina-This is a small tree, grown as an ornamental in the gardens. The plant is used for asthma, fevers and dropsy.
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25. Mussaenda luteola; This is a shrub of ornamental value.
26. Mitragyna parviflora; Verna-Kadam-This is a tree found throughout our country. A fibre is obtained from the bark which is used for cordage. The furniture, agriculture implements and carvings are prepared from its wood. The leaves are used as a fodder.
27. Morinda angustifolia; Verna-Banhardi-This is a large climbing shrub. The roots yield a yellow dye. The plants are found in the Khasia hills, Assam and Sikkim.
28. Oldenlandia umbellate; Eng-Indian madder; Verna-Saya-This is a herb, commonly found in Bengal, Orissa and South India. A red dye is obtained from the bark of its root.
29. Oldenlandia corymbosa; Verna-Daman paper-The decoction is used as a remedy for dysentery and cholera.
30. Randia dumetorum; Syn. Gardenia dumetorum; Verna-Mainphal-This is a large shrub or a small tree. The fruits are edible. The pulp of the fruits is used to cure dysentery. The plants are commonly found in Tamil Nadu, Maharashtra, Gujarat and Uttar Pradesh.
31. Randia uliginosa; Syn. Gardenia uliginosa; Verna-Pindalu-The fruits are edible and used for dyeing purposes. The leaves are used as fodder. The unripe fruits are used as a remedy for dysentery and diarrhoea. The plants are commonly found throughout the country except in the Northern India.
32. Rubia cordifolia; Verna-Manjit-This is a herb. A dye is extracted from its roots.
33. Rubia khasiana; A red dye is obtained from its roots.
34. Rubia sikkimensis-A red dye is obtained from its roots. It is used for dyeing both cotton and hair.
35. Rubia tinctorum-, Verna-Bacho-The roots of this plant also yield a red dye which is used for dyeing cloth. The plant is also used as fodder plant.
Systematic Relationships:
Bentham and Hooker included two families, i.e., the Caprifoliaceae and the Rubiaceae within the order Rubiales, Engler and Diels included five families in the order.
They are-Rubiaceae, Adoxaceae, Dipsacaceae, Caprifoliaceae and Valerianaceae. Hutchinson (1926) however, has placed the Rubiaceae and the Caprifoliaceae of Engler and Diels to his Asterales, but later on (1948) he modified his own view and placed these three families in a new order, the Valerianales.
According to him the Rubiales and the Valerianales are not at all related phylogenetically. According to him the Rubiales are derived from Loganiaceae and the Valerianales from Saxifragaceae.
