Leucas lavandulifolia Sm. (Lamiaceae): The Correct Name for Leucas indica of the Flo- ra of Bhutan

Abstract

Five Leucas species are reported in the Flora of Bhutan. During a floristic survey, specimens of Leucas lavandulifolia were collected from a subtropical forest in Sarpang District. The collected specimens were identified as Leucas indica (L.) Vatke, an illegitimate name as treated in the Flora of Bhutan. The correct name for the Linnaean species Leonurus indicus L. is Leucas lavandulifolia Sm. The species is placed in sect. Plagiostoma, which is characterised by an oblique calyx, a fan-shaped corolla lip, pedicellate nutlets, and distinctive exocarp cells. Leucas lavandulifolia can be distinguished from other closely related species in the genus by its obconical calyx, a puberulous and strongly oblique mouth, 8–10 calyx teeth with the apical tooth larger than the others, and oblong to oblong-obovate nutlets. It occurs in a wide range of habitats, including dry areas and roadsides, disturbed and agricultural fields, as well as moist sites, riverbanks, and thickets at forest margins. A key to the genus is also provided to facilitate accurate identification for conservation and management purposes.