Hook.f. & Thomson
Description
Clematis acutangula is an eastern Himalayan climber distributed through Bhutan, northern India, southern China and northern Myanmar, a comparatively restricted range reflected in the small number of GBIF records, about 61. It is a plant of temperate forest margins, scrub and thickets in the wetter montane ranges, scrambling over shrubs and into the lower canopy. The Bhutanese material photographed in the Haa (Haar) Valley at 3100 m in September documents the species in its upper-montane habitat, flowering at the close of the monsoon when many late-season Himalayan clematis come into bloom.
It is a woody to herbaceous climber whose stems are distinctly angular and sharply ridged, the feature from which the epithet acutangula derives. The leaves are opposite and compound, typically pinnate to biternate with ovate to lanceolate, toothed leaflets, the plant climbing by means of twining petioles and rachides. The flowers are nodding and campanulate, with four thick, recurved-tipped, petaloid sepals coloured yellowish to greenish-yellow, often tinged or dotted with purple; true petals are absent and the numerous stamens are enclosed within the bell. The fruit is a head of compressed achenes each bearing a long, persistent, plumose style that aids wind dispersal.
The species belongs to the autumn-flowering, yellow- to nodding-flowered assemblage of Asian Clematis allied to sect. Meclatis/Tubulosae groups, distinguished within the eastern Himalayan flora by its strongly angled stems and bell-shaped flowers. Its limited distribution and dependence on intact temperate forest scrub make it a characteristic but local element of the Bhutan-Sikkim montane flora; it is not formally assessed for conservation but its narrow range warrants attention.
Author: Hook.f. & Thomson · Sources: POWO (Kew), GBIF, Flora of Bhutan, Flora of China, Grey-Wilson's Clematis the Genus (monograph), Flora of British India