This family is very closely related to last week’s family Apocyanaceae. There are around 250 species in India.
The familiar examples are :
Mandar(Rui) Calotropis :Western and central India
Milkweed :Weed in most part of India
Tylophora Indica : Bengal and Assam
Vegetative characters : Perennial herbs (e.g.Asclepias) or shrubs (e.g.Calotropis) or woody climbers( e.g.Tylophora,Daemia).
Sometimes plants are succulent (Hoya) or xerophytic with cactus like habitat (Stapelia)
A perennial rootstock is commonly present and sometimes the roots are fleshy or tuberous. Plant contains a milky juice present in long branching laticiferous tubes.
Leaves are opposite decussate or rarely alternate, simple, entire and exstipulate.
Inflorescence is usually dichasial cyme arising in leaf axil or sometimes it is racemose or umbellate as in Asclepias and Calotropis. Flowers are perfect, hermaphrodite, actinomorphic, pentamerous and hypogynous. Calyx has five sepals united below to form a short calyx tube. Corolla is gamopetalous and usually five clefted or lobed but sometimes it is campanulate(e.g.Gymnema) or funnelform (e.g. Cryptostegia).
In Ceropegia the straight or curved corolla tube is swollen at the base. Corolla tube is often with a corona which is often in the form of ring of hairs scales or processes. Stamens are five, epipetalous. Gynoecium is bicarpellary. Ovaries are of two carpels free and so also their styles which are united by their apices and dilate to form a pellate stigma with five lateral stigmatic surfaces.
Fruit is of two follicles which are close together or divergent.
Seeds are flattened and commonly bear a terminal tuft of long silky hairs.
The flowers are perfectly adapted for insect pollination and seed dispersal is by wind.
Examples and economic importance:
Figure 1 Calotropis: Mandar or Rui :used in tanning industry.
Figure2 Milkweed Asclepius curassavica
Figure3 Pergularia daemia
Figure 4Wattakaka volubilis flowers
Figure5 Wattakaka volubilis fruit with seeds bearing hair tufts
Tylophora indica :roots are used in the treatment of Asthma,bronchitis etc.