Pontederiaceae
SHAHINA A. GHAZANFAR
National Herbarium, Agricultural Research Council,
Islamabad.
Fresh water and marshy perennial herbs; free floating or rooting. Roots adventitious. Leaves submerged or floating. Petioles sheathing at the base. Flowers bisexual, in racemes or spikes, subtended by a spathe-like leaf sheath. Perianth segments 6, free or united. Stamens (1-3-)6, epipetalous, filaments often unequal. Anthers equal or unequal. Ovary 1-3-locular, superior; ovules 1-numerous; placentation parietal, axile or pendulous. Style 1, stigma entire or lobed. Fruit a 3-valved capsule or a nut. Seeds ribbed.
A family of 6 genera and 30 species, mostly tropical in distribution, especially tropical Africa and America. Represented in Pakistan by 2 genera, one introduced.
Acknowledgements: We are grateful to the United States Department of Agriculture for financing this research under P.L. 480. Thanks are also due to Mr. I.C. Hedge of the Royal Botanic Garden, Edinburgh for going through the manuscript and giving valuable suggestions.
