五棱水蜡烛 wu leng shui la zhu

Herbs annual. Stems 10-40 cm tall, erect-ascending, base trailing, glabrous. Leaves in whorls of 4, linear to oblanceolate, 1-2 × 2.5-3.2 cm, glabrous, abaxially sparsely glandular, base attenuate, margin entire or slightly revolute, apex obtuse. Spikes subcapitate, 1-2.7 cm × 8-9 mm; bracts purple, lanceolate, slightly longer than calyx, margin gray villous. Calyx ca. 1 × 0.8 mm, pilose, glandular, 5-sulcate. Corolla reddish, ca. 2 × as long as calyx. Stamens much exserted. Nutlets unknown.

Aquatic, marshy streamsides; 900-1500 m. Yunnan [India]

Specimens from Yunnan do not have the slender, erect stems and slender spikes as described by C. B. Clarke for Indian plants. This may be due to local variation.