Hyobanche L. (Orobanchaceae) is a holoparasitic genus of ca. eight species endemic to southern Africa from the Cape Floristic Province northward to Namibia. There is a considerable amount of overlap in morphological characters among species resembling the most widely distributed species, H. sanguinea. There is also a high degree of similarity between H. glabrata and H. rubra, which differ primarily in the degree of exsertion of reproductive organs from the mouth of the corolla during anthesis. We investigated the species boundaries of Hyobanche using nucleotide sequence data from ITS and rbcL, ISSR markers, and morphological data. Our emphasis was on new collections from the 2001 field season, which included intensive population sampling in the Little and Nama Karoo, populations of H. sanguinea from coastal sand dune and limestone outcrop systems, and what appears to be a hybrid population between H. sanguinea and H. atropurpurea. A phylogeny reconstruction using ITS data reveals that H. rubra and H. glabrata from the Little Karoo form a distinct clade within a larger clade of populations from H. rubra and H. glabrata. Additionally, there appear to be few molecular and morphological characters separating H. rubra and H. glabrata. Molecular and morphological data also reveal unique characters for a taxon initially described as H. sanguinea from the Agulhas Plain.

Key words: Hyobanche, ISSR, Orobanchaceae, parasitic plant, phylogeny, South Africa