Survey of weed plant species used for medicinal purposes in four selected local government areas of oyo state

Survey was undertaken in four selected Local Government Area in Oyo state Nigeria in June 2010 to investigate weed plant species used for medicinal purposes. More than 70 different weed plant species were encountered in the study area, out of which 34 were found useful for medicinal purposes. Ageratum conyziodes Linn., Bryophyllum pinnnatum (Lam.) Oken, Occimum gratissimum L, Tridax Procumbens Linn, Chromolaena odorata (L) R..M. King & Robinson, Tithonia diversifolia (Hemsl.) A. and Morinda lucida Linn. were found to be the most frequently used of the weeds for medicinal purposes by 75% of the respondents. Nine of the 34 medicinal weeds (i.e 26.47%) were used in the study area for curing malaria, while 11.76% were used in curing body rashes. Convulsion and epilepsy were usually treated with 8.82% of the weeds, while 52.95% were used in curing either one or all of the above mentioned ailments. The findings also revealed that the majority (65%) of the weeds were present in all the zones. Most (65%) of the weeds are used in single herb form (by squeezing the fresh leaves to obtain the plant extract for drinking), while 20% of them were used in form of concoction ( i.e mixed with other ingredients). About 10 % were boiled as decoction to drink (Agbo) and 5% of them could be chewed or used as ointment to rub the affected part(s) of the body for fast relief.