Chemical constituents and inhibitory activities of essential oils fromCyperus brevifolius andC. kyllingia.

Cyperus brevifolius andC. kyllingia are two common weeds in Hawaii. The underground parts, including the rhizomes and roots, contain allelopathic essential oils, which may contribute to the aggressive spread of these weeds in grasslands and lawns. Although morphologically similar,C. kyllingia contains more essential oils thanC. brevifolius. Also, the former is rich in terpenes, including α-cyperone, β-selinene, and α-humulene, while the latter is rich in C17 to C25 n-paraffins. These chemical differences agree with their inhibitory activities against indicator species and the general observation thatC. kyllingia is the more prevalent weed of the two.