Oleaceae
(Olive family)
Plants of Oleaceae are usually shrubs (Syringa) or trees (Olea, Nyctanthes), occasionally vines (Myxopyrum smilacifolium). A family of about 29 genera and 600 species, Oleaceae are cosmoplitan but occur in great diversity in temperate and tropical Asia. Some largely represented genera of the olive family are:
- Jasminum,
- Chionanthus,
- Linociera,
- Fraxinus,
- Ligustrum,
- Syringa and
- Olea.
Selected Indian genera are:
- Nyctanthes,
- Jasminum,
- Fraxinus,
- Myxopyrum,
- Osmanthus and
- Olea.
Economic importance
Olive family is of considerable economic importance as a source of olives, olive oil, ash lumber, dyes and several ornamental plants.
- Notable ornamentals are various species of Jasminum (Jasmine), Syringa (lilac), Forsythia (golden bells), Ligustrum (privet), Osmanthus (fragrant olive), Philyrea, Chiananthus (fringe tree) and Nyctanthes.
- Olive (Olea europaea) has been a source of food since ancient times and the oil extracted from its fruit is of high value.
- Flowers of several species of Jasminum are source of an essential oil used in perfumery.
- Valuable timber is obtained from various species of Fraxinus (ash lumber), Notelaea and Olea.
- An orange dye used in colouring silk and cotton, is obtained from the flowers of species of Nyctanthes. Leaves of N. arbortristis (Har singar) are useful in fever and rheumatism.
Asclepiadaceae
(Milkweed Family)
A family of about 250 genera and 2000 species distributed mainly in tropical and subtropical regions and a few also in temperate regions. About 50 genera and over 250 species have been reported from India. Some larger genera are:
- Hoya (wax plant),
- Ceropegia,
- Asclepias (milkweed),
- Oxypetalum,
- Matelea (milkweed vine),
- Dischidia,
- Stapelia (carrion flower) and
- Periploca.
Selected Indian genera are:
- Asclepias,
- Calotropis,
- Cryptostegia,
- Leptadenia and
- Tylophora.
Plants of this family are herbs or vines with milky sap. Typically the filaments of stamens are connate into a short tube and their anthers are usually adherent or adnate to the stigmatic area of the gynoecium to form a complex structure called gynostegium or gynandrium. Anthers are two celled and their pollens are often united within each after sac into a structure called pollinium. Two pollinia, one each from the adjacent anthers are united together by two arms (retinaculae and translators) attached to a central gland called corpusculum. A nectariferous corona, consisting of five hoods may be present. These hoods are sometimes mistaken for petals. A beak or hood may be associated with each hood of corona.
Economic Importance
- Ornamental plants of this family grown in glasshouses include many species of Asclepias, Caralluma, Ceropegia, Cryptostegia, Hoya, Huernia, Oxypetalum, Periploca, Stapelia and Stephanotis.
- Fibre used for cordage, twines, fishing nets, is obtained from Asclepias curassavica (blood flower), Calotropis gigantea, Cosmostigma racemosa, Leptadenia pyrotechnica, Marsdenia roylei, M. tinctoria and Tylophora tennuis.
- Indigo like dye is obtained from Marsdenia tinctoria.
- Cryptostegia grandiflora has been cultivated commercially as a source of rubber.
- Latex obtained from species of Matelea is used as an arrow poison.
- Certain plants of Asclepiadaceae are of medicinal importance. These include,
- Calotropis procera, roots are used against cough,
- Gymnema sylvestre, used as a laxative and diuretic,
- Hemidesmus indicus, roots are used in urinary and skin diseases,
- Holostemma rheedianum, roots are used in cough and cold,
- Pergularia daemia, used as an emetic and expectorant,
- Sarcostemma acidum, infusion of roots is used as an antidote for snakebite and
- Tylophora indica, roots are used in curing bronchitis, whooping cough and asthma.
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