FOLIAR NECTARIES OF UNUSUAL STRUCTURE IN LEONARDOXA AFRICANA (LEGUMINOSAE), AN AFRICAN OBLIGATE MYRMECOPHYTE

Extrafloral nectaries of an African myrmecophyte, Leonardoxa africana (Baill.) Aubr., are disc-shaped, non-vascularized, embedded in the leaf mesophyll, and have a tiny neck extending to the abaxial leaf surface. These structural features differ from those found in other members of the Leguminosae, and represent an unusual type among flowering plants. These embedded foliar nectaries apparently have an energetic advantage over external nectaries and their presence supports the idea of independent and repeated evolution of nectaries in the legume family.