Benth.
Description
Leucas ciliata is a widely distributed Asian herb ranging across the Himalaya and into China, mainland Southeast Asia (Myanmar, Thailand, Laos, Vietnam), Bangladesh and beyond, with GBIF logging 573 occurrences over a broad set of countries including CN, IN, NP, BT, TH, MM, VN and BD. It is a plant of open, disturbed and seasonally moist ground, occurring on grassy slopes, forest margins, roadsides, scrub and cultivated land at low to mid elevations, generally up to about 2500 m. The photographed plant was recorded at Wangdi (Wangdue) Phodrang in west-central Bhutan around 2000 m, flowering in October at the close of the monsoon.
The species is an erect annual or short-lived perennial herb with the quadrangular stems typical of the Lamiaceae, clothed in spreading, often ciliate hairs. The leaves are opposite, ovate to lanceolate, toothed (crenate-serrate) and short-petiolate. The flowers are aggregated into dense, globose axillary whorls (verticillasters) subtended by bristly, ciliate bracts. Each flower has a tubular, ribbed calyx with spine-tipped teeth and a two-lipped white corolla in which the small upper lip is hooded and densely woolly outside while the larger lower lip is three-lobed; the four didynamous stamens lie beneath the galea. The fruit comprises four smooth nutlets enclosed in the persistent calyx.
Leucas is a large Old World genus of the subfamily Lamioideae, well represented in tropical Asia and Africa and characterised by woolly white corollas adapted to insect pollination. Several species, including L. ciliata, are used in traditional medicine. As a ruderal colonist of open and anthropogenic habitats it is common and widespread, and faces no conservation concern.
Author: Benth. · Sources: POWO (Kew), GBIF, Flora of Bhutan, Flora of China (Lamiaceae), Sebald revision of Leucas (Labiatae)