Peppermint oil composition and yield, flowering time, and morphological characters of four naturalised South Island clones and the Mitcham strain of Mentha piperita

Abstract

Four naturalised clones of peppermint (Mentha piperita L.) collected in the South Island were compared with the recently introduced Mitcham strain in a small field trial at Lincoln.

There were minor differences within the group of local clones in shape of leaf and inflorescence, flowering time, and oil composition, but they differed substantially from the Mitcham strain in these characters. The local clones were earlier in flowering, and higher in percentages of limonene, menthyl acetate, and terpenes eluting from the gas liquid chromatograph after menthyl acetate, and were lower in dry matter production and possibly in oil content.

Because of the lower oil yield from the local clones, it is recommended that commercial peppermint cropping be restricted to the Mitcham strain.