Annual herb, 0.08-0.50 m high, glabrous, erect, decumbent or diffuse. Leaves pinnate, subtended by 2 stipules; lower leaves 7-13-lobed; upper leaves smaller, with fewer lobes; lobes linear or filiform. Inflorescence a few-to many-flowered raceme. Flowers white, tinged with mauve or purple. Sepals narrowly ovate-oblong; outer 2 cucullate; inner 2 saccate, margins membranous. Petals obovate, papillate across the claw. Fruit moniliform. Seeds subcircular, narrowly winged.
Like H. meyeri but fruits larger, 15-50 x 2-3 mm with narrowly winged seeds, 2 mm diam.