Carpel Number as a Taxonomic Criterion in Pandanus

Abstract

One of the criteria sometimes used in distinguishing species in the genus Pandanus has been the number of carpels which make up each phalange of the fruit. An investigation of the dependability of this criterion yielded results which do not invalidate its use, but its applicability is restricted. In addition a more precise method of obtaining the information required for the use of the criterion is described, involving counts of carpels-per-phalange and phalanges-per-cephalium based on whole-cephalium samples. Graphs illustrate some of the variation with respect to carpel number in certain species of the genus. A specific example of the application of the criterion is provided, as are several other examples without detailed data. Cautious use of and limited dependence on the criterion are suggested, and some cases of variation in carpel number within one species are cited. Like all other taxonomic criteria, it should be used in conjunction with all other data and its applicability evaluated for each particular taxonomic case rather than depended upon for quick solutions to taxonomic problems.