Wall. ex G. Don
Description
Philadelphus tomentosus, the Himalayan mock-orange, is native to the temperate Himalaya, ranging from Nepal through Sikkim and Bhutan into northern India and SW China, with the many additional GBIF country codes (US, DE, BE, GB, PL and others) reflecting its wide cultivation as an ornamental shrub rather than a natural range. Some 388 occurrence records underpin this. The photographed plant was found at Lachung in northern Sikkim at about 2,600 m in June, at the onset of flowering. In the wild it is a shrub of temperate forest margins, ravines, open slopes and streamsides, typically between 1,800 and 3,000 m, often among mixed broadleaf and conifer woodland.
It is a deciduous shrub with arching branches and exfoliating bark on older stems. The leaves are opposite, ovate to ovate-lanceolate, acuminate, with a denticulate margin and three to five main veins from the base; the lower surface is densely tomentose with greyish hairs, a character giving the species its epithet. The flowers are borne in terminal racemes or panicles and are fragrant, with four white obovate petals, a cup-shaped hypanthium, four sepals and numerous stamens surrounding a four-locular inferior ovary tipped by partly divided styles. The fruit is a small woody capsule dehiscing loculicidally to release numerous minute seeds.
The genus Philadelphus is centred on the Northern Hemisphere and is taxonomically complex owing to hybridisation and horticultural selection; the leaf indumentum and floral dimensions distinguish P. tomentosus from related Asian species. Long valued in gardens for its scented blossom, it has naturalised in parts of Europe and North America. It remains common in its native montane forests and is of no conservation concern.
Author: Wall. ex G. Don · Sources: POWO (Kew), Flora of China Vol. 8, Flora of Bhutan Vol. 1, GBIF, Hu: A Monograph of the Genus Philadelphus