Species in the genus Isodon:

Isodon inflexus / Yamahakka
Isodon inflexus f. leucanthu / Shirobanayamahakka
Isodon japonicus / Hikiokoshi
Isodon longitubus / Akichouji
Isodon longitubus f. albiflora / Shirobanaakichouji
Isodon shikokianus var. intermedius / Takakumahikiokoshi
Isodon shikokiana var. occidentalis / San'inhikiokoshi
Isodon shikokiana var. occidentalis f. albiflorus / Shirobanasan'inhikiokoshi
Isodon trichocarpus / Kurobanahikiokoshi
Isodon umbrosus / Inuyamahakka

Isodon inflexus / Yamahakka ヤマハッカ

Isodon inflexus, a perennial of 0.4-1m in height, occurs at the forest edges in fields and mountains. Leaves are opposite; the margins are coarsely serrated, in the shape of a broad oval, each 3-6cm in length, the base abruptly becoming narrow to follow the wing portion of the petioles. Blue-purple flowers, 7-9mm in size, bloom in slender spikes - upper lips cleft in four, lower lips shape a boat. Bloom time: September-October.