Notes For Reference:-

Mentha arvensis / Hakka ハッカ

Mentha arvensis, a 20-60cm tall perennial herb found in somewhat damp places, extends many long rhizomes to propagate, with vellus hairs on stems, leaves, and calyxes. The leaves are opposite, 2-8cm long, 1-2.5cm wide, long and narrow, with pointed tips, sharply serrated margins, and glandular spots on the undersides. Axils on the upper parts have 4-5mm-long whorls, light-purple flowers. Calyxes cut themselves into five segments, and the segments pointed. Bloom time: August-October.