A short-lived herbaceous plant developing a basal rosette of leaves at first. Its upright branched stems are hairy and grow up to 2 m tall. Its lower leaves (4-15 cm long) are elongated in shape with bluntly toothed to deeply lobed margins. Its smaller upper leaves are usually long and narrow with finely toothed or entire margins. Its small flower-heads (5-10 mm across) do not have any obvious 'petals' and turn off-white and fluffy as they mature. Its small 'seeds' (1-2 mm long) are topped with a tuft of pale brown or yellowish hairs about 3 mm long.
Widely naturalised in south-eastern Queensland, and particularly common in the Moreton district. Widely naturalised other parts of Australia (i.e. New South Wales, the ACT, Victoria, Tasmania, South Australia, many parts of Western Australia, and other parts of Queensland). Also naturalised on Lord Howe Island and Norfolk Island.
A very common weed of roadsides, disturbed sites, waste areas, parks, gardens, lawns, footpaths, pastures, fallows, crops, coastal environs, riparian vegetation, forest and wetland margins, and disturbed woodlands.
A short-lived (i.e. annual or biennial) herbaceous plant developing a basal rosette of leaves at first. It later produces a single upright (i.e. erect) stem up to 2 m tall, with several branches in the uppermost portion.
The greenish stems are covered in hairs (i.e. hirsute). The larger rosette leaves are borne on stalks (i.e. petioles) to 4 cm long. These leaves (4-15 cm long and 0.5-2.5 cm wide) are narrowly egg-shaped in outline (i.e. ovate), narrowly oval (i.e. elliptic) or elongated (i.e. lanceolate) with bluntly toothed (i.e. crenate) to deeply lobed (i.e. pinnatifid) margins. Leaves that are produced along the stems are alternately arranged and have shorter stalks, while those towards the tops of the branches are more or less stalkless (i.e. sessile or sub-sessile). These uppermost leaves (3-6 cm long and 3-10 mm wide) are smaller and usually more elongated in shape (i.e. linear) with entire margins.
The small flower-heads (i.e. capitula) are borne in large numbers in leafy clusters (i.e. in racemes or racemose panicles) in the upper one-third of the plant. These flower-heads (5-10 mm across and 4-6 mm long) do not have any obvious 'petals' (i.e. ray florets). They have numerous tiny cream or yellowish coloured flowers (i.e. tubular or disc florets) that are surrounded by a few rows of green bracts (i.e. an involucre). These bracts (4-5 mm long) are long and narrow (i.e. linear or lanceolate). Flowering occurs throughout the year, but mainly from summer through to winter. As the 'seeds' (i.e. achenes or cypselae) mature, the flower-heads become fluffy, globular in shape, and turn pale brown or off-white in colour. These tiny oblong 'seeds' (1-2 mm long and about 0.5 mm wide) are topped with a tuft (i.e. pappus) of straw-coloured or off-white hairs about 3 mm long.
Tall fleabane (Conyza sumatrensis) reproduces only by seed, which are easily blown and dispersed by the wind. Seeds may also be spread by machinery, water, vehicles, animals, and in clothing and contaminated agricultural produce.
There are several other fleabanes (Conyza spp.) present in the region, the most common being flaxleaf fleabane (Conyza bonariensis), Canadian fleabane (Conyza canadensis var. pusilla) and Chilean fleabane (Conyza primulifolia). These species can be distinguished from tall fleabane (Conyza sumatrensis) by the following differences: tall fleabane (Conyza sumatrensis) is a relatively large plant and grows up to 2 m tall, with toothed leaves. Its flower-heads are relatively small (5-10 mm across and 4-6 mm long) and off-white when mature (i.e. they often have a slight brownish or yellowish tinge).flaxleaf fleabane (Conyza bonariensis ) is a moderately-sized plant, usually less than 1 m in height, with toothed and curled leaves. Its flower-heads are relatively large (6-12 mm across and 5-6 mm long) and when mature they turn whitish in colour.Canadian fleabane (Conyza canadensis var. pusilla) is a moderately-sized plant, usually about 1 m in height, with toothless leaves. Its flower-heads are noticeably smaller (3-5 mm across and 3-4 mm long) and off-white when mature (i.e. they often have a slight brownish or yellowish tinge).Chilean fleabane (Conyza primulifolia) is a relatively small plant, usually less than 80 cm in height. Its flower-heads are noticeably larger (15-20 mm across and 8-12 mm long) but are produced in small clusters.