THE MORPHOLOGY AND DEVELOPMENT OF THE FRUIT OF HETEROMORPHA (APIACEAE)

Fruits of the Apiaceae are generally bilaterally symmetric (disymmetri c), i.e., the two mericarps are identical, so that they are symmetrica l at the commissural plane. Some genera, however, have zygomorphic (mo nosymmetric) fruits, where the single plane of symmetry is perpendicul arto the commissural plane. In the nine Heteromorpha species from the African mainland, the zygomorphy results from the expansion of all fiv e sepaline ribs to form wing-like structures (the five petaline ribs n ever develop to the same extent). This peculiar wing symmetry is alrea dy evident at the flowering stage. The eight Heteromorpha species from Madagascar have disymmetric fruits and their inclusion within the gen us is questionable. We suggest that the Heteromorpha-type wing configu ration is an apomorphic condition which supports the monophyly of the mainland species.