Department of Botany, University of Karachi, Karachi-75270
Annual or perennial, terrestrial, epiphytic or aquatic herbs. Roots present or absent. Stem (stolons) short and delicate in terrestrial and epiphytic while usually more robust and long in aquatic species. Leaves alternate, opposite or verticillate, sometimes rosulate, entire or divided, sometimes polymorphic, covered with glandular hairs (Pinguicula) or with bladders (Utricularia). Inflorescence racemose, simple or sparingly branched or in some aquatic species supported on the water by a whorl of modified spongy leaves (floats). Flowers showy, hermaphrodite and zygomorphic. Calyx 2-5 lobed, persistent. Corolla gamopetalous, 2-lipped usually spurred or saccate. Stamens 2, attached at the base of corolla throat; filaments often winged, short, usually curved; anthers 2-celled, dorsifixed, cells diverging or confluent. Ovary superior, 1-locular; carpels 2; style usually short, persistent; stigma ± 2-lipped; ovules many, on free central or free basal placenta. Fruit a capsule, indehiscent or opens by 2-4 valves, pores or circumcissile. Seeds minute, without endosperm.
A family of 3 genera and c. 300 species, mostlyin the tropical and the temperate northern hemisphere. Represented in Pakistan by single genus and 3 species, distributed from plains to mountains up to ± 4000 m.
Acknowledgements: We are grateful to the authorities of the following herbaria for herbarium and library facilities: Royal Botanic Gardens, Kew (K); Reading University Herbarium (RNG) and National Herbarium, Islamabad (RAW). We are indebted to Prof. C.D.K. Cook (Botanisher Garten and Institut fur Systematische Botanik der Universitkt Zurich, Switzerland) and Mr. Rizwan Yusuf Hashmi (CDRI,Karachi) for going through the manuscript and offering suggestions for its improvement. The financial assistance received from the U. S. Department of Agriculture under P.L.480 with the coordination of the Pakistan Agricultural Research Council, Islamabad, is thankfully acknowledged.