Biennial herbaceous. Root typically globose or elongated, outer colour white, white with purple or yellowish. Almost no stem before it flowers. Leaves up to 30 cm long, glaucous, sometimes lyrate. Inflorescence stem with lobed leaves. Flowers with 4 yellow petals, arranged in corymbose clusters.

Upright herbaceous plant up to 1.7 m high, glabrous and glaucous. Alternate, oblong to obovate leaves up to 35 cm, tripinnate with the last filiform segments; petiole pods 1-3 cm long. Inflorescences with terminal and lateral umbels; numerous flowers with yellow petals. Fruit ovate-elliptic, glabrous, up to 4 mm long, compressed dorsally, narrowly winged ribs, the 2 lateral ones are broader.

This species is often confused with Foeniculum vulgare, which has a longer petiole pod and all the ribs of the fruit are the same.

Annual plant, very aromatic, erect, up to 2 m in height, covered with long hairs. Alternate or opposite bipinnatifid leaves, 3 to 10 cm in length. Greenish male flowers in long terminal buds, female flowers in leaf axils. Fruit in ovoid, angular and thorny achenes, 3 to 4 mm in length.

Shrub or small tree of up to 9 m, very ramified. Alternate leaves, ovate, from 8 to 20 cm, acuminate, cordate at the base, entire. Inflorescence in terminal panicles; flowers 4 to 5.3 cm in diameter; pink or white petals, obovate to broadly oval. Capsule (fruit) ovoid to globular-ovoid, 3 to 4 cm, usually with soft spines. Seeds with a red aril.