Abstract
A morphometric analysis of Sri Lankan Aponogeton was performed in order to clarify species delimitations and to facilitate their identifications by comparing states coded for 61 vegetative and reproductive characters. Both cluster analysis and principal coordinate analysis resolved five discrete phenetic groups within the genus in the island. Four of these clusters corresponded well with the four previously reported species (A. rigidifolius, A. jacobsenii, A. crispus and A. natans) whereas a fifth cluster delimited a new Aponogeton species, A. dassanayakei, from the wet lowland regions of Sri Lanka. These analyses have disclosed more useful characters for field identification of the species.