A delicate annual herb with transparent stem
Stems little branched, or with short suppressed lateral shoots (consisting of a few nodes only) in the leaf-axils, glabrous, often with orange or reddish glands in the epidermis.
Leaves on the upper 1/2–2/3 of the plant usually with the largest lamina and the longest petioles; leaves of a pair equal or subequal; stipules membranous, translucent and very inconspicuous, triangular, usually less than 1 mm. long; petiole 0.5–4 cm. long; lamina ovate to elliptic, (0.3–)1–3.5(–4.5) cm. long, (0.2–)0.8–2(–3.5) cm. wide, base cuneate, rounded or subcordate, margin serrate, with 3–8(–13) teeth on each side (usually restricted to the apical 2/3 of lamina), apex shortly acuminate; lateral nerves 3–4 pairs, basal pair reaching 2nd–3rd tooth from leaf-apex; both surfaces glabrous, upper surface with white dots between the numerous linear cystoliths.
Female flowers subsessile; perianth ± 0.8 mm. long, 3-merous, with 1 long, ovate perianth-segment with an apical swelling, the 2 others much shorter, 3 hyaline staminodal scales present, shorter than ovary.
Achene ovate to lanceolate, compressed, 0.8–1 mm. long, pale brown.
Inflorescences usually 2 together in the upper leaf-axils, spike-like, with dense cymose clusters along an axis up to 1.5 cm. long, rarely the axis branched to form a paniculate inflorescence, or with only 1 cluster on a peduncle (occasionally 1 inflorescence and 1 reduced shoot with a few nodes in a leaf-axil).
Male flowers either in small, separate, cymose, globular inflorescences or in small clusters at the base of ♀ inflorescences; the ♂ flowers usually develop early, on pedicels ± 0.8 mm. long; perianth ± 0.8 mm. in diameter, 3–4-merous, each tepal with a subapical swelling.