Description: Herb with rhizome, stem to 1.5 cm; tomentose on petioles, leave beneath, inflorescences, bracts, pedicels and outside calyx. Leaves opposite, congested; blade elliptic, ovate or obovate, 2–9.8 cm long, pale brown beneath; apex obtuse to rounded; base unequal; margin crenate; secondary veins 5–9 on each side, sunk above; tertiary venation reticulate, visible on both sides; petioles 0.3–9 cm long. Inflorescence axillary, compound cyme, few to many-flowered; peduncles 4.5–17 cm long; bracts ligulate, to 3 mm long; pedicels to 1.2 cm long. Calyx shortly connate; lobes 5, triangular, 1–2.5 mm long. Corolla white, flat, slightly bilabiate with short tube; upper lip 2 lobes, slightly smaller than lower lib; lower lip 3 lobes, elliptic, 2.7–5 mm long. Stamens 2, inserted above corolla base; filaments 1.5–3 mm long, straight, with minute glands; anthers dorsifixed, glandular dorsally, longitudinally dehiscing; staminodes 2 or absent. Ovary ovoid, 2–2.5 mm long, papillose; style 2.5–3.8 mm long, glabrous; stigma capitate, papillose. Capsule twisted, 0.7–1.4 mm long, papillose. Seeds numerous, small.

Thai name: ชาฤๅษี (cha ruesi)

Photos: Preecha Karaket (Chiang Mai)