Interestingly, plants in Piperaceae family also had allelopathic activity. The methanolic extract of Piper samentosum Roxb. 0.01 g/mL inhibited seedling growth of Medicago sativa L. (Pukclai and Kato-Noguch 2011). The powder of Kava (Piper methylsticum L.) inhibited seed germination of Lectuca sativa L. and paddy weeds (Echinochloa crus-galli) and Monochoria vaginalis Presl. (Hong, Xuan et al. 2002). The allelochemicals in extracts was identified and reported (Amri, Hamrouni et al. 2013). β-Caryophyllene at 3.0 mg/L significantly inhibited the germination rates and seedling growth of Brassica camperstris and Raphanus sativus (Wang, Peng et al. 2009).