Among the root parasitic angiosperms in the family Scrophulariaceae, Striga gesnerioides (Willd.) Vatke (= S. orobanchoides Benth.) has been reported in the old world tropical regions of Africa and Asia (Hutchinson and Dalziel, 1954). In Nigeria, S. gesnerioides is a parasite of cowpea {Vigna unguiculata) whose yield is consequently considerably reduced. Reports on the observations of haustorial development in S. gesnerioides are scanty. Based on the examination of herbarium specimens, Kuijt (1969) reported that S . gesnerioides has no secondary roots and, therefore, has no secondary haustoria. Ozenda and Capdepon (1972) collected and studied the haustorial systems of S. gesnerioides populations parasitic on Euphorbia beaumierana in Morocco and confirmed the observations of Kuijt (1969). Thus, attention was drawn to the unique features of S. gesnerioides which 'differ strongly from the other Striga species, since it is holoparasitic and connected to its host by a single, conspicuous and complex haustorium which probably represents the most advanced type among the family Scrophulariaceae' (Ozenda and Capdepon, 1972). While studying the haustorial systems of S . gesnerioides we found a number of morphological features, here reported, which differed from published facts. In order to obtain various stages of infection of the host root by the parasite, 0*5-1-0 g of 1-year old S. gesnerioides seeds were mixed into the top 4-10 cm of good garden soil or washed sand in 14 cm diameter earthenware pots. At the same time two cowpea seeds were sown per pot and these were thinned to one after germination. The pots were watered twice daily and maintained under natural daylight in a greenhouse having average daily maximum and minimum temperatures of 31 ± 2 °C and 22 ± 2 °C respectively. After 6-9 weeks of growth, a number of parasite shoots had emerged above the soil surface, with the characteristic scale leaves closely adpressed to the stem. The shoots (stem and leaves) turned green in light. Some parasite shoots, which were allowed to grow for a longer period, produced flowers characteristic of Striga gesnerioides. At various stages of development, the cowpea plants were washed free of soil and the haustoria at various stages of development were isolated and studied. The earliest stage of initial infection observed (Plate 1a) shows a swollen pole of the parasite radicle at the point of host root penetration. At this stage, the plumular pole of the embryo is still enclosed in the black seed coat. A later stage (Plate 1b) shows a welldeveloped primary haustorial bulb and a shoot with scale leaves. In more advanced parasite seedlings, secondary roots are formed from the base of the shoot (Plate lc, d, e). These secondary roots on making contact with the host root to which the primary haustorium is attached (Plate Id), or other host roots (Plate If), establish secondary haustoria. It was also observed that secondary haustoria could be established where two parasite secondary roots came into close contact (autoparasitism).