Jan Bastimeijer and Joseph Bogner weighed in on C. cordata
and using karyotype (= number of chromosomes) evidence have made a significant and sensible - given what we know - reclassification; there are still forms that have not gone expensive DNA analysis yet and almost certainly more forms of this highly variable plant still to be found.
So, the new breakdown goes like this:
- C. cordata cordata is the 2n=34 krayotype and found in Southern Thailand, Penninsular Mayalsia and one known location in Sumatra. Mostly acid-loving blackwater plants.
- C. cordata siamensis is the form from Thailand with a chromosome compliment of 2n=68,85,102 and forms exist that live in acidic black water while other forms exist from limestone biotopes and do well in hard water.
- C. cordata grabowski is the n=68 other form from Borneo, nearly all of which are from black water peat swamps.