historically, the myrtaceae were divided into two subfamilies. subfamily myrtoideae (about 75 genera) was recognized as having fleshy fruits and opposite, entire leaves. most genera in this subfamily have one of three easily recognized types of embryos. the genera of myrtoideae can be very difficult to distinguish in the absence of mature fruits. myrtoideae are found worldwide in subtropical and tropical regions, with centers of diversity in the neotropics, northeastern australia, and malesia. in contrast, subfamily leptospermoideae (about 80 genera) was recognized as having dry, dehiscent fruits (capsules) and leaves arranged spirally or alternate. the leptospermoideae are found mostly in australasia, with a centre of diversity in australia. many genera in western australia have greatly reduced leaves and flowers typical of more xeric habitats.