Parnassiaceae
MOHAMMAD AMIN SIDDIQI
Department of Botany, Gordon College, Rawalpindi.
Perennial, glabrous, scapigerous herbs. Leaves simple, mostly radical, exstipulate, alternate, petiolate with basal nerves and brown streaks con¬taining tanin cells in the epidermis, cordate, reniform or ovate, cauline leaves sessile or subsessile. Scape arising in the axil of a leaf, often bearing a single leaf, and a solitary terminal flower. Flowers regular, hermaphrodite, 5-merous. Sepals 5, free or somewhat united at the base, imbricate. Petals 5, free, white, imbricate, entire or sometimes fimbriate. Stamens 5, alter¬nating with petals; staminodes 5, opposite the petals. Gynoecium 3-4-car¬pellary, syncarpous, superior or rarely half inferior, usually 3-4-celled below, 1-celled above; placentation axile below, parietal above. Fruit a membr¬anous loculicidal capsule, opening by 3-4 valves, surrounded by persistent staminodes; seeds many, minute, non endospermic.
A north temperate family with a single genus and about 50 species, spread over the Arctic, N. temperate regions of Europe, N. Asia and N. America in wet places. Previously included in Saxifragaceae from which it is characterized by a conspicuous whorl of branched staminodes tipped with pseudo-nectaries, by the ovary which is unilocular above with 3-4 parietal placentas and becomes 3-4-Locular below with axile placentas. It is sometimes also included in Droseraceae. Represented by only 4 species in the northern regions of W. Pakistan.
Acknowledgements: We are grateful to the United States Department of Agriculture for financing this research under P.L. 480. Thanks are also due to Messrs B.L. Burtt, I.C. Hedge and Miss J. Lamond of the Royal Botanic Garden, Edinburgh, for their helpful suggestions.
