Aquatic or semi-aquatic fern, up to 1 m tall, floating or rooted in soil, with short, erect rhizome and rosette-like tuft of leaves. Leaves dimorphous; sterile leaves with succulent petiole 5–50 cm long, sparsely scaly with broad, pale brown scales, filled with air canals, lamina of sterile leaves 1–3-pinnate, up to 20 cm × 40 cm, membranous, glabrous, with evident anastomosing veins, often provided with adventitious buds in axils of pinnae, pinnae irregularly shaped, ultimate lobes linear-oblong to elliptical; lamina of fertile leaves erect, 2–4-divided, up to 100 cm × 50 cm, ultimate lobes linear, margin revolute, covering the sporangia scattered individually along the veins. Spores tetrahedral, 95–125 μm in diameter, pale yellow, translucent, with irregular reticulum.

Styptic (leaves and roots)

PROTAbase: Ceratopteris thalictroides

The leaves and roots are used medicinally to stop bleeding and as a poultice against skin complaints, e.g. as a drawing agent on carbuncles.