Cryptocoryne cordata
Plant usually unifoliate; spathe tube white-green, unstriped outside and inside; spathe mouth margins widely recurved and light green; spathe limb plain carmine outside, paler inside, with a white spot at throat level surrounded by light green margins; spadix appendix smooth and glabrous inside the tube.
Chromosome number: 2n = 34, 68, 85, 102. Previous reports (Arends & al., op cit.) of chromosome numbers of 2n = 68 and 85 in C. cordata, have not been definitely verified in recently studied accessions from southern Thailand.
Notes. — The identity and circumscription of C. cordata has been a matter of discussion for a number of years. Recently C. grabowskii Engl. (Borneo), C. zonata De Wit (Borneo), and C. diderici De Wit (Sumatra), all with a chromosome number of 2n = 68, have been referred to C. cordata at the variety level (Jacobsen, 2002)., Since 2002, however, much more material from Borneo has become available for study and the distinction between var. grabowskii and var. zonata at least seems not to be tenable.
The east coast collections with a chromosome number of 2n = 34, cordate leaves and a long spathe tube are referred to var. cordata and the west coast collections with a chromosome number of 2n =102, ovate leaves and a short spathe tube are referred to var. siamensis.