Weed Identification

Australia > > Narrow-Leaf Cotton Bush

Narrow-Leaf Cotton Bush

Gomphocarpus fruticosus

Alternative Name(s): Swan Plant

Family: Asclepiadaceae.

Form: Herb

Origin: Native of Africa, Arabia and Mediterranean.

Flowers/Seedhead: Inflorescence a drooping umbel of flowers. Flowers all year round.

Description: Erect perennial shrub to 2 m high. Stems densely covered with apressed short weak soft hairs when young, becoming hairless with age. Leaves 412.5 cm long, 0.51.5 cm wide, upper and lower surfaces with scattered hairs; on leaf stalk to 1 cm long. Fruit a green pod initially, turning brown with age, covered with soft spines to 1 cm long, splitting to release seeds; pod with inner wall separated from outer wall by an air space and seeds within inner chamber; pod stalk S-shaped. Seeds numerous, ovoid, flat, about 0.6 cm long and ending in a tuft of white silky hairs about 3 cm long.

Distinguishing features: Distinguished by shrub habit; milky latex; lanceolate opposite leaves; flowers white to cream; fruit a thin walled inflated ovoid pod, 47 cm long, 1.53 cm wide, ending in a tapering point.

Dispersal: Spreads by seeds and lateral roots.

Confused With: Balloon Cotton Bush, Gomphocarpus physocarpus, that has ball-shaped pods without a tapering point and Broad-Leaf Cotton Bush, Gomphocarpus cancellatus, that has inner surface of pods without spines.

Inflated fruit with long soft bristles, white
flowers, caterpillar of Wanderer Butterfly
photo I.Walker

Notes: Poisonous to stock, but seldom eaten. Hybridises with Balloon Cotton Bush with hybrids intermediate in appearance. Cotton Bush is a preferred food for caterpillars of the Wanderer Butterfly, Danaus plexippus, but they do not control the plant.


    Noxious Weeds of Australia. W. Parsons and E. Cuthbertson, 1992, pages 179182.

Wanderer Butterfly
Danaus plexippus

Pods & seeds with silky hairs

Linear leaves & inflated pod

This weed has been included in the WEEDeck field guide as card H32

More information about WEEDeck is available from Sainty & Associates Pty. Ltd.


Australia > > Narrow-Leaf Cotton Bush


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