(Kurz.) Bremek.
Description
Pavetta tomentosa var. glabrescens is a shrub of the warm subtropical and tropical forests of southern and southeastern Asia. GBIF records the species across a broad range encompassing India, Thailand, China, Myanmar, Nepal, Laos, Vietnam, Cambodia, Malaysia, Indonesia, Sri Lanka, Bangladesh and Bhutan, with some 530 occurrences. It grows in deciduous and semi-evergreen forest, woodland margins and scrub at low to mid elevations. The photographed material derives from Nepal in the Gorkha district at Labubhesi, around 1100 m, in May, a humid montane-foothill setting near the lower Himalayan slopes that marks the northern edge of its distribution.
The plant is an erect, branching shrub with opposite, simple, elliptic to oblong leaves that are entire, shortly petiolate and, in the typical variety, softly tomentose; in var. glabrescens the indumentum is reduced and the foliage tends towards near-glabrous, the distinguishing feature of the variety. Interpetiolar stipules are present, as is characteristic of Rubiaceae. The white, fragrant flowers are borne in dense terminal corymbose cymes; each has a four-lobed salverform corolla with a slender tube and a long, far-exserted style, the hallmark of Pavetta. Bacterial leaf nodules, harbouring nitrogen-related endophytes, occur as dark dots in the lamina. The fruit is a small globose, two-seeded berry, ripening black.
GBIF accepts the species, the variety reflecting the glabrescent extreme of a tomentose-pubescent continuum. Bremekamp, who monographed the genus, recognised numerous such infraspecific entities. The genus is notable for its near-obligate bacterial leaf symbiosis. Widespread and ecologically tolerant, the species is of no conservation concern.
Author: (Kurz.) Bremek. · Sources: POWO (Kew), GBIF, Flora of Nepal, Flora of China, Bremekamp monograph of Pavetta