Introduction

The order Malvales has traditionally included four core families, Bombacaceae, Malvaceae, Sterculiaceae and Tiliaceae, although various authors have included other families such as Cistaceae and Cochlospermaceae. Recent phylogenetic studies (e.g., Alverson et al. 1998, Bayer et al. 1999) have revealed that the four core families form a monophyletic group, termed here the core Malvales, and have identified ten allied families which are included in the expanded Malvales shown in the tree above. Together, these families contain approximately 4,000 species and range from small Mediterranean shrubs like Cistus to towering tropical trees like Shorea. The order also contains many economically important plants, such as Cola (the source of cola flavor), Bixa orellana (annatto, a natural red coloring), Theobroma cacao (the source of cocoa) and Gossypium (cotton) and Ochroma pyramidale (balsa wood).