(Hook.) Meisn.
Description
Boenninghausenia albiflora is a delicate, aromatic herb of the Sino-Himalayan and East Asian region, recorded by GBIF from China, Japan, Taiwan, the Himalaya and Southeast Asia, with more than 5600 occurrences attesting to its frequency. It grows on shaded forest floors, mossy banks, rocky stream gullies and clearings in temperate and subtropical woodland, often on humus-rich or stony ground. The photographed population occurs in Bhutan in the Haa Valley at about 3100 m, flowering in September toward the end of the monsoon; the species ranges broadly from around 1000 to 3500 m across its Himalayan distribution.
The plant is a glabrous, gland-dotted perennial or subshrub with slender, much-branched stems woody only at the base, the whole exuding the citrus-rue scent characteristic of the family. The leaves are alternate and two- to three-pinnately compound, the small ultimate leaflets obovate to oblong, thin, glaucous beneath and conspicuously pellucid-punctate. Numerous small white to cream flowers are borne in lax terminal panicles, each with four petals, eight long-exserted stamens, and a gynophore-borne ovary. The fruit comprises four spreading follicle-like carpels that dehisce to release small reniform seeds.
Boenninghausenia is a small genus of the Rutaceae allied to Ruta, distinguished by its herbaceous habit and stipitate ovary. The pellucid oil glands contain volatile compounds and coumarins, and the plant has a history of use in traditional medicine and as an insect repellent. Variable in leaf division and stature, it has been split into several infraspecific taxa across its wide range. It is common and of least concern, readily recolonising disturbed shady ground.
Author: (Hook.) Meisn. · Sources: POWO (Kew), GBIF, Flora of China, Flora of Bhutan, Rutaceae monograph (Hartley)