ABSTRACT
Tropical forest trees are the largest and most diverse, but least studied group in this Handbook, covering tens of thousands of woody species, belonging to some 85 families. 73 For instance, more species may be present in 25 ha of lowland forest in Malaysia than in the whole flora of the U.S. 119 During the last decade, more information has become available on reproductive phenology and periodicity in both natural forests and plantations, but knowledge of controlling factors is still extremely scanty. Attention will therefore be focused on considering the most fruitful approaches to the difficult problems of studying forest trees, sketching the variety of their reproductive behavior in the tropics, and indicating some of the factors known or likely to affect flowering (including coning of coniferous species).
