136 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



COMPARISON OF ESSENTIAL CHARACTERS. 



The curious external resemblance of a ripened pistil of Phytelephas 

 to the fruit clusters of Nipa and Pandanus, which may have been 

 the original cause of the whole confusion, is only curious and ex- 

 ternal. Each of the cones or pyramids that make up the fruit 

 cluster in Nipa and Pandanus represents a separate fruit, from a 

 distinct flower, whereas the cones and pyramids of Phytelephas are 

 merely so many coarse warts on the skin of a fruit that represents 

 the large compound pistil of one flower. There is a real correspond- 

 ence or approximation between Nipa and Pandanus, but it is not 

 shared at all by Phytelephas, except as appearances are taken in the 

 most superficial way. 



Whether Nipa is to be reckoned as a true palm or not, it certainly 

 represents a family very distinct from the Pandanaceae, in spite of 

 the similarity of the fruit clusters. The many Nipa fruits that have 

 been recovered from Eocene deposits in England and other parts of 

 Europe show that the type is an old one, not a recent derivative from 

 some other group of palms. The family differences that separate 

 the Nipaceae from other Asiatic palms, such as the Borassaceae. do 

 not indicate an alliance with Phytelephas or other American palms. 

 Even the numerical peculiarities of Phytelephas are not shared by 

 Nipa, which has only three stamens and three carpels, and only a 

 single seed developed from each (lower. 



The pistil of Phytelephas is remarkable for the number of carpels, 

 which ranges from four to nine. Most of the palms have only three 

 carpels, ami usually only one is matured, with a single seed. In 

 the coconut and its relatives all the carpels share in the formation 

 of the husk and the bony shell of the fruit, but two of the ovules 

 are usually aborted. The mature coconut has only one endosperm 

 and one embryo. Nevertheless, in the genus Attalea, a rather close 

 relative of the coconut, the development of two or three ovules is u 

 frequent occurrence, and some of the South American species of 

 Attalea produce additional carpels, so that the ripe nut contains 

 four, five, or six kernels, each in a separate chamber of the thick 

 shell. 



In the number of carpels, as in the number of stamens, Phytele- 

 phas is unique only in the sense of furnishing an extreme of a 

 series. Species that have only 4 to G carpels do not transgress the 

 range of diversity shown in other palms. The addition of a few 

 more carpels makes Phytelephas appear the more different from 

 other palms, but does not compel us to relegate it to the Pandana- 

 ceae or to erect it into an independent group in order to show T a very 

 wide divergence from other type's of palms. 



Though Phytelephas is undoubtedly different from other palms, 

 some of the other palms appear to have more affinity with Phytele- 



