A morphological study of the fruit and seed of certain southern African members of the Anacardiaceae

Abstract

The Anacardiaceae is a natural family which is grouped into five tribes. Two of these occur in southern Africa. The Spondieae is represented by Harpephyllum Bernh. ex Krauss, Lannea A. Rich. and Sclerocarya Hochst. and the Rhoideae by Heeria Meisn., Laurophyllous Thunb., Loxostylis Spreng. f. ex Reichb., Ozoroa Del., Protorhus Engl., Rhus L. and Smodingium E. Mey. ex Sond. Although this study focusses mainly on the three species of the Spondieae and Rhus lancea L.f., observations on other species, e.g. of Heeria, Mangifera L., Operculicarya H. Perr. and Tapirira Aubl., are also described. The thesis includes reprints and manuscripts of scientific papers, dealing mainly with the ontogeny and structure of the fruit and seed. The taxonomic significance of characters is stressed, supplemented with notes on evolutionary trends and seed germination. A comprehensive review of the literature is provided, including comments on the structure and function of the hypostase and occurrence of the pachychalaza. The exocarp of the drupe in Anacardiaceae may be thin (R. lancea) or thick, representing an exocarp sensu lato (Sclerocarya). The mesocarp is characterized by conspicuous secretory ducts and usually differentiates after endocarp lignification. The endocarp is usually a sclerocarp. It is either stratified (R. lancea) or non-stratified (Spondieae). Opercula are restricted to the members of the Spondieae with well-developed sclerocarp.