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Dioscoreaceae

MOHAMMAD AMIN SIDDIQI


Botany Department, Gordon College, Rawalpindi.

Dioscorea deltoidea
Illustration

Credit: M.Y. Saleem

Tall, slender, herbaceous or woody, climbing, dioecious perennial, herbs or shrubs with tuberous rhizomes, root-stocks or thick woody stem tubers. Leaves exstipulate, petiolate, alternate, rarely opposite, simple or compound; lamina variously shaped, multicostate, reticulate. Flowers bracteate, inconspicuous, in axillary spikes, racemes or panicles, unisexual, monochlamydous regular, actinomorphic. Male flowers: perianth 6-lobed, tubular at the base; stamens 6, in 2 series, or sometimes only 3, arising from the base of the perianth-tube. Female flowers: perianth 6, polyphyllous, persistent, superior; gynoecium tricarpellary, syncarpous ; ovary inferior, trilocular with axile placentation, rarely unilocular with parietal placentation, usually with 2 anatropous ovules in each locule; styles very short, free or connate; stigma terminal, simple or bifid, reflexed. Fruit a 3-winged, loculicidal capsule, sometimes a berry. Seeds often compressed and winged, endospermic.

A family of 5 genera and about 750 species distributed over tropical and warm temperate regions of the world. Represented by only 1 genus in W. Pakistan. Separated from Smilacaceae by its inferior ovary, and spicate or racemose flowers.

Acknowledgments: We are grateful to the United States Department of Agriculture for financing this research under P.L. 480. Thanks are also due to Messers B.L. Burtt, I.C. Hedge and Miss J. Lamond of the Royal Botanic Garden, Edinburgh for critically going through this manuscript and making useful suggestions.

Lower Taxon


 

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