(Buch.-Ham. ex D.Don) H.Hara
Description
Isodon lophanthoides is a widespread herb of the Sino-Himalayan region, recorded from China, the Indian Himalaya, Nepal, Bhutan, Pakistan, Myanmar, Thailand, Laos, Vietnam, Bangladesh, Malaysia and Hong Kong, and represented by nearly two thousand georeferenced collections. It occupies a broad subtropical to warm-temperate belt, growing on moist shaded banks, forest margins, streamsides, grassy slopes and disturbed ground. In Bhutan it descends to warm river valleys, as along the Mo-Chu at about 1800 m where it was photographed flowering in October, the late-season anthesis typical of the genus.
The plant is an erect to ascending annual or short-lived perennial herb with quadrangular, often purple-tinged and pubescent or glandular stems. The leaves are opposite, ovate to broadly ovate, crenate-serrate, acuminate, and narrowed at the base into a winged petiole, often gland-dotted beneath. The inflorescence is a lax, much-branched terminal panicle of small cymes. The flowers have a bilabiate, glandular calyx that enlarges in fruit, and a small two-lipped corolla that is white to pale pink or purplish, dotted with darker spots, with a flat lower lip and four declinate didynamous stamens. The fruit consists of four smooth ovoid nutlets (mericarps).
Isodon (formerly included in a broad Rabdosia and Plectranthus) belongs to subfamily Nepetoideae of Lamiaceae; this species was described as Plectranthus lophanthoides by Buchanan-Hamilton and transferred by Hara. Several intraspecific varieties have been recognised across its range. Rich in bioactive ent-kaurane diterpenoids, it is used in Chinese herbal medicine, and its broad ecological tolerance and frequency mean it is not of conservation concern.
Author: (Buch.-Ham. ex D.Don) H.Hara · Sources: POWO (Kew), GBIF, Flora of China, Flora of Bhutan, Flora of Pakistan, taxonomic revisions of Isodon (Lamiaceae) by H. W. Li