Embryology and systematic relationships of Kiggelaria (Flacourtiaceae)

Abstract

Kiggelaria L. is endemic to Africa and the only representative of tribe Pangieae (Flacourtiaceae) on the continent. Molecular genetics, phytochemistry and host-parasite relationships have indicated a relationship between this woody, pantropical tribe of Flacourtiaceae and a small, trigeneric family of herbaceous, southern African endemics, the Achariaceae. In the present study, ovule and seed structure in Kiggelaria were investigated and compared with relevant data recently reported for Achariaceae. Support for an alliance with Achariaceae were found in the presence of anatropous, bitegmic. sessile ovules with zigzag micropyles. deep-lying embryo sacs covered by an epistase in the ovule and seed, endotestal-exotegmic seed coat layers, suspensorless embryos and sarcotestal seed with a prominent, plate-like hypostase. Unlike Achariaceae.  Kiggelaria seeds do not have chalazal seed lids, pronounced raphal ridges, a fringe layer, or stomata in the outer epidermis of the sarcotesta. Structural dissimilarities in seeds of omithochorous  Kiggelaria and myrmeco- chorous Achariaceae were regarded as adaptations linked to adifferent strategies for seed germination and dispersal.