Thai native waterlilies survey as an evidence to support ‘Jongkolnee’ waterlily (Nymphaea siamensis) in new subgenus

An exploration was conducted to investigate native waterlilies which might be related to ‘Jongkolnee’ in Thailand. ‘Jongkolnee’ waterlily was given a scientific name as Nymphaea siamensis. Some waterlilies were highly specific for their habitat, such as ‘Bua Bae Kao’ (Nymphaea sp.) and a native tropical night blooming waterlily growing in Phu Sa Dok Bua National Park in Yasothon province were found to be rare. Studies of Nymphea siamensis revealed their characters that suggested its possible placement in an entirely new subgenus. ‘Nilubon’ or ‘Bua Bae Muang’, found in Roi Et province, showed similar morphology to ‘Bua Khap’, another native waterlily. However, ‘Bua Bae Muang’ produced bulblets; while, ‘Bua Khap’ did not produce any bulblet. Morphological and genetic comparison between N. siamensis and other Nymphaea species, including imported waterlily; Nymphaea colorata, were conducted. ‘Bua Bae Muang’ showed the closest similarity to N. siamensis. They showed similar leaf, stem, and root morphology and ‘Bua Bae Muang’ also produced bulblets. However, its flowers were purple petals with complete reproductive organs; while, N. siamensis lacked reproductive organ. Random amplified polymorphic DNA comparison revealed that N. siamensis was most similar to ‘Bua Bae Muang’ and ‘Bua Bae Kao’. N. siamensis has no sexual reproductive structures and is propagated only via bulblets. Under condition of subgenus taxa system in genus Nymphaea, species are categorized into subgenera by their ovary characters: apocarpous ovaries, or syncarpous ovaries. But N. siamensis has no ovaries; therefore, it could not be categorized into any existing subgenera.