The taxonomic value of fruit structure in the subfamily Saniculoideae and related African genera (Apiaceae)

All members of Saniculoideae sensu stricto are unique in their fruit structure, having the endocarp non-lignified, outgrowths on mericarps, usually prominent intrajugal secretory ducts, vallecular vittae totally absent, commissural vittae absent except in Lagoecia L. (which should be better placed in Apioideae), carpophore absent except in Alepidea F. Delaroche, and crystals dispersed throughout the mesocarp. The fruits of the African genus Lichtensteinia Cham. & Schltdl. are very similar to those of Saniculoideae, having very prominent intrajugal secretory ducts and lacking both vallecular and commissural vittae (the endocarp of one mericarp is lignified, the other not). Furthermore, scattered crystals are present in the mesocarp. Three other African genera (Arctopus L., Polemanniopsis B.L. Burtt and Steganotaenia Hochst.) also have some fruit characters that are similar to those of Saniculoideae, such as the total absence of vallecular and commissural vittae, combined with intrajugal cavities (which are enormous in the latter two genera). They differ in some respects, such as nearly always having lignified endocarps, non-functional intrajugal secretory ducts forming cavities, wings (in Polemanniopsis and Steganotaenia), and an absence of crystals. A cladistic analysis based on all anatomical characters shows that Lichtensteinia, Polemanniopsis and Steganotaenia are directly basal to the Saniculoideae, and that there is sufficient morphological evidence (in support of earlier molecular systematic studies) to expand the circumscription of the subfamily to include these genera.