Plectranthus eriocalyx Dunn, Plants perennial, herbs or shrubs, 0.5-3 m tall. Stems reddish, densely appressed pubescent. Petiole 0.6-5 cm; leaf blade ovate-oblong to ovate-lanceolate, 2.5-18 × 0.8-6.5 cm, papery, sparsely pubescent on veins, base broadly cuneate to rounded, abruptly attenuate, margin crenate-serrate to crenate-dentate, sometimes entire, apex acuminate.Panicles spikelike, terminal and axillary, 2.5-35 cm × ca. 1 cm, densely whitish floccose-puberulent; cymes compact, many flowered. Calyx campanulate, 1.5-1.8 × 1.8-2 mm, gray lanate, glabrescent; teeth ovate, subequal, ca. 1/3 as long as calyx; fruiting calyx straight, dilated, ca. 4 mm. Corolla purplish or purple, 6-7 mm, pilose outside. Style included or sometimes exserted. Nutlets dull yellow, ovoid. Fl. Jul-Nov, fr. Nov-Dec.

Studies on the methanol extract of Rabdosia eriocalyx leaves have resulted in the isolation of a highly oxidized abietane diterpenoid glycoside, eriocaside A, and its structure determined by means of 2D COSY, HMBC and ROESY NMR spectroscopy.