A taxonomic synopsis of Nymphaea nouchali Burm. f. And infraspecific taxa

Nymphaea nouchali exhibits a range of flower colours, where some taxonomic circumscriptions consider the character as of taxonomic significance in recognising infraspecific taxa. The revision of the Sri Lankan Nymphaeaceae has not recognised any infraspecific taxa. N. nouchali populations exhibiting morphological variations within a range of floral colours were encountered during the field studies conducted in different parts of the country. Therefore, the present study was conducted with the objective of evaluating the morphological variations of N. nouchali populations using multivariate analyses of morphological and molecular sequence data. Both morphometric analysis using 59 characters and matK and trnH-psbA sequence data supported two subgroups within N. nouchali, clearly corresponding to the differences in flower colour; one group with blue flowers and the other with white and pink flowers. In addition, colour of the petiole and the leaf abaxial surface also supported the grouping. The study recognised two infraspecific taxa for N. nouchali in Sri Lanka, N. nouchali var. nouchali with blue flowers [‘Nil-manel’ (S); Blue water-lily (E)] and N. nouchali var. versicolour (Sims) Guruge and Yakandawala with either white or pink flowers. Recognising infraspecific taxa of N. nouchali in Sri Lanka is significant to the country not only to acknowledge its natural diversity, but in addition most importantly, as N. nouchali is the declared national flower of Sri Lanka. In this context, the recognition of the blue-flowered group as N. nouchali var. nouchali would strengthen its identity over the other flower-colour groups of N. nouchali. A taxonomic key for the Sri Lankan Nymphaea and descriptions for the two infraspecific taxa are also produced.