Weed control measures and policies often view weedy plants as problem species that interfere with agricultural productivity. This results in these plants being eradicated sometimes indiscriminately without regard for their other economic importance. In rural Central Kenya however, people are turning to use of traditional medicinal plant species that include important weeds. This study analyzed the use of weed species in contemporary traditional medicine in Central Kenya. The results show that 75 species in 34 plant families are used as sources of traditional medicine for 59 ailments. Informant consensus analysis for the ailments cited reveal that 32 of these ailments have a consensus factor of 0.5 and above. These weed species therefore deserve to be considered as important plants when Kenyan government is legislating problem plants species. In resource use efficiency variation and management of this variation are crucial and hence agrobiodiversity conservation strategies should include weedy species of medicinal value. Indigenous as well as non-indigenous weed species were found to form part of the Central Kenya pharmacopoeia. This implies that traditional medicine in this region may be undergoing changing patterns as far as medicinal plant utilization is concerned. The medicinal weed species used for the treatment of ailments with high informant consensus need to be incorporated in agroecosystems in this region as domesticated plants or plants in the process of domestication. Further study of these plants especially phytochemical and pharmacological studies may contribute to development of important pharmaceutical products in future.
