Distribution of Rhamnaceae:
Rhamnaceae or Indian jujube family or Buckthorn family includes 58 genera and about 900 species. The plants of this family are cosmopolitan in distribution.
Economic Importance of Rhamnaceae:
- Food: The fruits (fresh or dry) of Zizyphus spp. (Z. jujuba syn. Z. mauratiana) Z. vulgaris, and Sageretia oppositifolia are edible.
- Medicinal: Rhamnus purshiana (bark) yields Cascara sagrada, a laxative; Rhamnus frangula also yields a laxative called Frangula.
- Wood: Krugiodendron ferzeum yields the hardest and heaviest of wood known as black iron wood. Zizyphus chloroxylon yields a valuable hard wood. Frangula alnus also yields a valuable timber.
- Dye: Green and yellow coloured dyes are obtained from Rhamnus infectoria, R. chlorophora and Ventilago spp. The dyes are useful for colouring silk goods.
- Cordage: The bark of Ventilago denticulata is used for making cordage.
- Charcoal: Gun powder (Dog-wood) is prepared from the wood of Zizyphus mauritiana and also of Rhamnus and Frangula.
- Ornamentals: Species of Ceanothus, Reynosia, Noltea, Collectia, Discaria etc. are grown for decorative purposes.
Affinities of Rhamnaceae:
Bentham-Hooker’s placed Rhamnaceae under the Celastrales after the Geraniales and before the Sapindales. Rhamnaceae and Vitaceae are closely related families forming the natural series Rhamnales; the common scandent and climbing habit occur in both the families. Perigynous structure with the reduction of one of the perianth whorls together with tendency of unisexuality and disc formation are also striking features.
The order Rhamnales including two families Vitaceae and Rhamnaceae was included in the order Celastrales by Bessey as Celastrales is closely allied to Rhamnales. Both Hallier and Bessey support the origin of Rhamnales and Celastrales from Rosales. According to Rendle both Rhamnales and Celastrales probably had parallel origin from diplostemonous order resembling Rutales. Hutchinson (1959) put both Celastrales and Rhamnales in Lignosae near to each other, he traced the origin of Celastrales and Rhamnales as parallel series from Euphorbiales.