Common Australian Garden Weeds

Lepidium bonariensis

Scientific name: Lepidium bonariensis L.


The flowers, immature fruit and upper leaves of Argentine peppercress (Lepidium bonariensis).


Seedling of Argentine peppercress.


An Argentine peppercress plant in the rosette stage.


Close-up of the immature flattened elliptic fruit of this species.

Common name: Argentine peppercress

Family: Brassicaceae

Origin:

Native of South America.

Habit:

Annual or biennial herb, first forming a rosette of leaves, later producing erect flowering stems up to 60 cm tall.

Habitat:

Common weed of tended areas.

General description:

Stems and leaves

Leaves of the rosette have a stalk (petiole) and have highly divided leaf blades ( ie. 2-3 pinnatisect) up to 6 cm long. Upper leaf blades are cut into lobes about halfway to midrib (pinnatifid). Stem and leaves are covered in long hairs.

Flowers and fruit

Flowers are tiny with four petals shorter than the sepals which are 0.5-1 mm long. Flowers are borne in spikes at the ends of the flowering stems. Flowering season is mainly spring to summer. Fruits are flattened pods, broadly elliptic in shape 3-4 × 2.5-3.5 mm on stalks 2-4.5 mm long.

Distinguishing characteristics:

Annual or biennial herb developing a rosette of highly divided leaves, later sending up erect flowering stems up to 60 cm tall with leaves that are less divided than lower ones. Flowers are tiny, whitish borne in spikes at the tips of the erect stems. This plant can be distinguished from Lepidium africanum (common peppercress) by its highly divided leaves and its conspicuous hairiness.

Noxious status:

Not noxious.

Sources:

Kleinschmidt, H.E., Holland, A. and Simpson, P. (1996). Suburban Weeds. 3rd Edition. Department of Primary Industries, Brisbane.

Stanley, T.E. and Ross, E.M. (1983-1989). Flora of South-eastern Queensland. Volume 1. Department of Primary Industries, Brisbane.

Auld, B.A. and Medd, R.W. (1996). Weeds: An Illustrated Botanical Guide to Weeds of Australia. Inkata Press, Sydney.