Geographical distribution and aspects of the ecology of the hemiparasitic angiospermStriga asiatica(L.) Kuntze: a herbarium study

Striga asiatica(Scrophulariaceae) is an obligate root hemiparasite of mainly C4grasses (including cereals). It is the most widespread of the 42Strigaspecies occurring in many semi-tropical, semi-arid regions of mainly the Old World. Examination of herbaria specimens revealed thatS. asiaticahas a wider geographical distribution, is present at higher altitudes and occurs in a more diverse range of habitats than previously reported. The host range is also larger than previously reported and is likely to include a large number of C3plants. Morphology of examined specimens revealed variation in size and corolla colour suggesting the existence of ecotypes. Climate may exert a significant influence on the distribution ofS. asiaticagiven the diversity of potential host plants and their distribution beyond the current recorded range ofS. asiatica.