Caryota - The BIG Ones
These enormous fishtail palms have caused great problems in classification because it is almost impossible to make reference collections for the herbarium that show the differences that may be obvious in the field. Thus type specimens on which the names are based are often very difficult to interpret. Here's my interpretation for what it is worth.
Caryota laoensis is easy to deal with - the name has never been validly published so should not be used - I've no idea what is being traded as such.
Caryota obtusa was described way back in the 1840s by William Griffith from northeast India. We know that there is a huge Caryota there, which, from photographs, seems indistinguishable from the huge Caryota of S Yunnan, Laos and northeast Thailand - these ranges are near enough to each other to suggest a contiguous distribution, probably also in Burma. The population in China was called C. urens in the Flora of China but is very obviously not that species. In Thailand the palm was called C. gigas by Don Hodel. It is my belief that the NE Indian, Chinese, Lao and Thai populations are one and the same and should therefore probably be called C. obtusa .
However, to complicate matters there is a second large Caryota in northeast India, and who is to say that this one is not the true C. obtusa ! We need a very careful revision of the genus based on extensive field work.
Caryota maxima is much more straightforward - this is a big palm of Java, Sumatra, Penisnular Malaysia and S. Thailand, that grows in the mountains. It was also called by C. obtusa var aequatorialis and C. aequatorialis - and hence the confusion with C. obtusa . You can read about C. maxima , C. no and a few other species in Principes 18:87-93.
I hope this helps - John Dransfield
(from a posting to the IPS's Palm Talk, by Dr. John Dransfield).