The genus Rubus in South Africa. III. The occurrence of apomixis and sexuality

Abstract

The genus Rubus L. contains two ovules per ovary, one above the other. The embryo sac developing in the upper ovule degenerates. The lower ovule contains either aposporic or sexual embryo sacs. In some species degeneration of sexual embryo sacs was observed. With the exception of R. apetalus Poir., apospory is absent in the subgenus Idaeobatus Focke. Since all South African Rubus species have sexual embryo sacs, with the exception of R. flagellaris Willd. where all sexual embryo sacs eventually degenerate, they have the potential to act as pollen receptors during hybridization. The morphological differences between the embryo sacs of different species are not sufficient to distinguish between species. Die genus Rubus L. bevat twee saadknoppe per vrughok. Die twee saadknoppe is bo-op mekaar geleë. Die kiemsak in die boonste saadknop degenereer altyd. Die onderste saadknop kan geslagtelike of aposporiese kiemsakke bevat. In sommige spesies is degenerasie van geslagtelike kiemsakke waargeneem. Met uitsondering van R. apetalus Poir., is aposporie onbekend in die subgenus Idaeobatus Focke. Aangesien alle Suid-Afrikaanse spesies van die genus Rubus geslagtelike kiemsakke bevat, met uitsondering van R. flagellaris Willd. waar sodanige kiemsakke mettertyd degenereer, besit hulle die potensiaal om as moederplante in kruisings op te tree. Die morfologiese verskille tussen die kiemsakke van verskillende spesies is te min om tussen die spesies te onderskei.