Jameson 550 and 551 have the same collection site. Some of the original labels of the specimens in Paris (P), which were used as the holotypes of P. pachystachya and P. stenostchya, were swapped which made it impossible to C. de Candolle to judge what number belonged to what collection. So, de Candolle mentioned both numbers in the protologues of both taxa (which would actually make them nomenclatural synonyms). Comparing with duplicates in other herbaria has solved this puzzle. Jameson 550 is the type of P. pachystachya and Jameson 551 is the type of P. stenostachya [Mathieu, 2005].