Rubiaceae is one of the largest families consisting of nearly 500 genera and more than 6,500 species. They are widely distributed in the tropical and sub-tropical regions. In India, this family is represented by 76 genera and more than 274 species.
Mostly trees (eg. Cinchona officinalis, Morinda tinctoria) or shrubs(eg. Mussaenda) or herbs (eg. Rubia).
A branched tap root system.
Aerial, erect, cylindrical, woody and branched but herbaceous in Rubia.
Simple, opposite decussate (eg. Ixora coccinea) or whorled (eg.Galium), entire and stipulate. The stipules of opposite leaves are fused at the node between the petioles. They are called interpetiolar stipules (eg. Ixora coccinea). When the stipules of each leaf are fused at the angle between petiole and stem, they are called intrapetiolar stipules. (eg.Gardenia).
Mostly terminal or axillary cymose (eg. Gardenia) or corymbose cyme (eg. Ixora coccinea) or cymes are aggregated into dense head as in Anthocephalus indicus (Kadamba tree).
Bracteate, bracteolate, pedicellate, dichlamydeous, complete, tetra or pentamerous, actinomorphic and epigynous.
Sepals 4 or 5, gamosepalous rarely polysepalous, showing valvate aestivation. In Mussaenda, one of the sepals is brightly coloured. It is called petaloid sepal.
Petals 4 or 5, gamopetalous, hypocrateriform or salver shaped i.e. a long narrow tube consisting of limbs x placed at right angles to the tube (eg. Ixora coccinea), showing valvate or twisted or imbricate aestivation.
Stamens 4 or 5, alternate with petals, epipetalous and inserted at the mouth of corolla tube. Anthers are dithecous, basifixed, introrse and dehiscing longitudinally.
Ovary inferior, bicarpellary and syncarpous. Ovary bilocular with one or numerous ovules in each locule showing axile placentation. Style simple, stigma bilobed or capitate. There are five carpels in Gardenia.
A berry (Ixora coccinea) or a capsule (Cinchona officinalis) or a multiple fruit (Morinda tinctoria).
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