Differences in the vascular skeleton of the flower within a genus have been described more than once. The known examples show as a rule a variety of degree in reduction or fusion of vascular traces (Fames 1931). Sometimes floral anatomy can help to distinguish the species in a genus, as in Boerhavia, where the absence of a bundle in the perianth segments in one of the two common species is specific (Puri 1952). When studying the development of the ovaria in some Lythraceae I came across the apparently fundamental difference in placental vascularisation described here.