Comparative floral ontogeny in Detarieae (Leguminosae: Caesalpinioideae). 2. Zygomorphic taxa with petal and stamen suppression

Marked floral zygomorphy and a reduced number of petals and/or stamens are the character traits that distinguish the taxa described (species of Afzelia , Berlinia , Gilbertiodendron , Macrolobium , Neochevalierodendron , Paramacrolobium , Phyllocarpus , and Tetraberlinia ). All have an “Omega”‐shaped floral apex after bracteole initiation, bracteoles large when initiated, helical sepal initiation, unidirectional petal initiation (simultaneous in Afzelia , not determinable in Tetraberlinia ), and unidirectional stamen initiation. Floral zygomorphy is expressed primarily by one petal being much larger than the others and by suppression of several of the stamens. Five petals are initiated in all; suppression begins in late development. Either two petals ( Neochevalierodendron , Phyllocarpus ) or four petals ( Afzelia , Berlinia , Macrolobium , Tetraberlinia ) are suppressed. All ten stamens are initiated; at midstage, suppression begins in either three stamens ( Afzelia ) or seven stamens ( Gilbertiodendron , Macrolobium , Paramacrolobium ). Other expressions of zygomorphy may include diadelphy, stamen filament connation late in development, or displacement of the carpel from a central position to the adaxial side of the hypanthium. There is no loss of organs similar to that which occurs in some other Detarieae.