Rubina Dawar

Casuarina equisetifolia Illustration

Monoecious or dioecious trees or shrubs. Branchlets slender, jointed and striate. Leaves reduced to whorls of small scales, united at base, forming many-toothed sheaths at the nodes; internodes with striate grooves corresponding to the number of leaves. Flowers minute, grouped into unisexual silicate or capitate inflorescence. Male spikes usually terminal on lateral branches. Female heads globose or ovoid, usually subsessile and axillary. Bracts whorled, each having a sessile flower and each flower is subtended by a pair of bracteoles. Male flowers with solitary stamen, hooded by 1 or 2 tepals. Female flowers without perianth; ovary minute, 1-loculed; style short with 2 long filiform stigmas. Infructescence globular, ovoid or cylindrical, ± woody, formed by enlargement of bract and paired bracteoles which become more elongated enclosing the fruit and open at maturity like valves. Fruit a single seeded flattened, terminally winged samara. Seeds exalbuminous; embryo straight with large flat cotyledons.

A family with 4 genera and c.70 species mostly distributed in Australia but extending also over SE. Asia and Polynesia. Represented in Pakistan by a single genus and 3 species known from cultivation only.

Acknowledgements: We are grateful to the authorities of Royal Botanic Gardens, Kew for herbarium and library facilities.

Lower Taxon

• Casuarina L.