ARILS AND ARIL‐LIKE STRUCTURES IN WOODY RANALES

Abstract

The arils and aril‐like structures of one species of all woody Ranalean families, in which ‘arils’ are reported, have been investigated ontogenetically and comparatively. In Myristicaceae and some Annonaceae soft enations occur on the seeds, in Siparuna (Monimiaceae 8.1.) on the carpels, and in Hedyosmum (Chloranthaceae) even on the outer side of the flower. In these examples both the evolutionary possibilities, convergence and transference of function, are compared. It seems that the different sites of such enations are due to convergence, whereas the change of the dispersal units themselves and of their protecting organs are due to transference of function. We are drawn to the conclusion that arils are probably neither especially primitive nor homologous in all angiosperms, because such convergences already occur within one single order–an order which is generally considered, moreover, to be particularly primitive. Copyright © 1973, Wiley Blackwell. All rights reserved