Further Thoughts on Dioecism and Islands

Non-dioecious taxa are the floral majority, both in island floras and in those of the mainlands.This is true at all latitudes.Temperate zone islands have very low percentages of dioecious species.The percentages are somewhat higher in subtropical islands.Relatively high percentages of dioecism are found only in moist tropical islands or in floras that have had a moist tropical influence on their composition.Low islands in the tropics and rather arid islands in the sub-tropics and tropics have only small numbers of dioecious species in their floras.A multiple regression analysis shows that latitude and maximum height of islands together account for 82% of the variation in percentage of dioecism in our samples.Although autochthonous development of dioecism ge of dioe immigrant cannot be ruled out yet, the percenta in an hermaphrodite