A perennial, 20-40 cm tall, erect to suberect, hairy to glabrescent herb. Leaves opposite or rarely alternate, with 4-12 mm long petiole; lamina lanceolate-rhomboid ovate, 1-2.5 cm long, 4-15 mm broad, cuneate or subtruncate at the base, entire, acute; stipules broadly ovate, c. 4-5 mm long, c. 3-4 mm broad, acuminate, ciliate. Flowers pale green, in loose axillary clusters, covered with simple or uncinate hairs, female sessile, male with c. 2 mm long pedicel. Calyx 4-lobed and gibbous in male; 4-toothed in female flowers. Stamens 4. Achenes ovate, c. 1.5 mm long, shining black, enveloped by ribbed calyx.