Jan Bastimeijer and Joseph Bogner redescribed C. cordata and using karyotype (= number of chromosomes) evidence and have made a significant and sensible reclassification; there are still forms that have not undergone expensive DNA analysis yet and almost certainly more forms of this highly variable plant are yet still to be found. The first two decades of the 20th century saw an explision of COR morphtypes. Just to give you an idea of the numebers involved there were maybe a dozen species of Crypts at most while as of this writing (2019) there are about seventy different known locations of COR many of which look rather different; some live only in rainwater and rotting leaves, others live in hard water. Some are a couple of inches others are over two feet tall.
But, their 2012 reclassification goes like this:
C. cordata cordata is the n=34 karyotype and found in Southern Thailand, Penninsular Malaysia and one known location in Sumatra. Mostly acid-loving blackwater plants.
C. cordata siamensis is the form from Thailand with a chromosome compliment of n=106 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 form from Borneo, "nearly all of which are from black water peat swamps" according to Basteimeijr, but there is evidence of this form growing in rivers full of pebbles up in he mountains near Dayu. These plants are large and not bullate, many forms in peat swamps are bullate. Certainly there are minor divisions still within C. grabowski that can be made.
