(Blume) Faden
Description
Rhopalephora scaberrima is a tropical to subtropical spiderwort widely distributed across South and Southeast Asia, recorded from India, Nepal, Bhutan, Bangladesh, Sri Lanka, Myanmar, Thailand, Malaysia, Indonesia, the Philippines, Vietnam, southern China and Taiwan. Its GBIF profile, with about 1,104 occurrences spanning these countries, confirms a broad Indomalayan range. The plant illustrated was photographed in southern Bhutan at Zhemgang at about 910 m in October. It is a species of warm, humid lowland and lower-montane settings, growing in forest understorey, along shaded streambanks, in moist grassy clearings and on disturbed roadsides, generally below about 1,500 m where high rainfall and warmth prevail.
It is a perennial, somewhat straggling herb with ascending to decumbent stems that root at the lower nodes, the surfaces and leaf-sheaths conspicuously scabrid-hispid, as the epithet indicates. The leaves are alternate, ovate-lanceolate to elliptic, with a closed sheathing base and an acuminate apex. The flowers are borne in small scorpioid cymes aggregated into a terminal panicle; each has three free sepals and three blue to violet petals, with the androecium showing the differentiation characteristic of the family, the fertile stamens separated from reduced staminodes. The fruit is a small loculicidal capsule, distinctively two-locular with the seeds arranged in two rows, a key feature separating Rhopalephora from related genera.
The genus Rhopalephora was segregated from the broadly defined Aneilema and Commelina on the basis of its bilocular capsule, biseriate seeds and stamen architecture, as clarified in Faden's revisionary work. As a common and adaptable plant of disturbed humid habitats, R. scaberrima is not threatened and serves as a useful indicator of warm, moist forest edge in the eastern Himalayan foothills.
Author: (Blume) Faden · Sources: POWO (Kew), Flora of China Vol. 24, Flora of Bhutan Vol. 3, GBIF, Faden: Commelinaceae (revisionary studies)