Scientific name: Conyza spp.

Common name: Fleabanes, ragweeds

Family: Asteraceae

Origin:

Natives of South America.

Habit:

Annual herb developing a rosette of leaves at first and then a single flowering stem which branches with inflorescences up to 1 m tall.

Habitat:

Widespread weed of tended areas such as gardens and lawns, also in disturbed sites, roadsides etc.

General description:

Stems and leaves

The erect stem grows up to 2 m in height and branches into leafy panicles. Basal leaves have petioles (leaf stalks) to 4 cm long and are narrowly ovate to elliptic (up to 10 x 1.5 cm). The stem leaves near the base of the plant have petioles. As the leaves are produced further up the stem the length of petioles gets shorter, towards the ends of branches leaves are sessile. The stem leaves can have the same shape as the basal leaves, or they can be linear, and stem leaves are smaller. Stem leaves are alternately arranged on the stems. Plants are usually hairy, with long soft hairs, often with short rough hairs as well.

Flowers and fruit

Flower-heads are 5-10 mm across when mature. They are fluffy and whitish, without petals (ray florets). The inflorescence is sparsely branched and leafy. The seeds are achenes 0.5 x 1.5-2 mm with a pappus (tuft) of long fine hairs 3 mm long. Flowering occurs from spring until autumn.

Distinguishing characteristics:

Fleabanes (Conyza spp.) are annual herbs with soft hairy coarsely toothed leaves, usually with a single stemmed flower stalk with fluffy flowering heads. There are three fleabanes (Conyza spp.) that are most common in Australia and they can be difficult to tell apart. Conyza canadensis (Canadian fleabane) can be distinguished from C. bonariensis (flaxleaf fleabane) and C. sumatrensis (tall fleabane) by its smaller flower-heads ie. 5 mm diameter vs. 10 mm diameter. While C. bonariensis and C. sumatrensis differ in stature, the former is usually a metre in height while the latter is usually over 2 m tall. Also the leaf margins of C. bonariensis have more pronounced lobes.

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 2. Department of Primary Industries, Brisbane.

Friend, E. (1983). Queensland Weed Seeds. Department of Primary Industries, Brisbane.

Anonymous. (1994). Queensland Vacsular Plants: Names and Distribution. Queensland Herbarium, Brisbane.

Wilkinson, R.E. and Jacques, H.E. (1980). How to Know the Weeds. 2nd Edition. W.C. Brown Co., Iowa.