Summary
A detailed chromosome study has been made of 58 species in 30 genera of the tropical family Meliaceae. The results largely confirm observations, by other investigators on similar tropical woody groups, that high chromosome numbers are common and that polyploidy is a frequent phenomenon. Although the chromosomes are, in most species, very small and metacentric, some differences in chromosome size and shape are detectable. Many genera seem to have a high base number and/or several different numbers. The Meliaceae, unlike some other tropical woody groups, are particularly interesting because of the considerable range of chromosome numbers they exhibit. Differences in number have been observed between even closely related species in the economically important timber genera Swietenia, Cedrela and Toona, and this has an obvious bearing on future tree breeding and tree improvement studies. The taxonomic significance of chromosome numbers is discussed.