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Scale bar 10mm. Copyright CSIRO
Cotyledon stage, epigeal germination. Copyright CSIRO
Habit, flowers and fruit. Copyright CSIRO
10th leaf stage. Copyright CSIRO
Conyza canadensis (L.) Cronquist
Cronquist, A.J. (1943) Bulletin of the Torrey Botanical Club 70: 632. Type: ?.
Erigeron canadensis L., Species Plantarum: 863(1753), Type: ?.
Fleabane; Hogweed; Canadian Flea Bane; Butterweed; Horseweed
Usually flowers and fruits as a shrub about 1-2 m tall but occasionally flowers when smaller.
Leaf blades variable in size and shape, about 2-10 x 0.3-0.8 cm, hairy on both the upper and lower surfaces. Teeth sparse, about 7 or 8 on each side of the leaf blade. Stems or twigs hairy and longitudinally ribbed.
Flower heads less than 5 mm diam. at anthesis consisting entirely of disk florets subtended by an involucre of persistent bracts. Flowers in the outer ring are female with hermaphrodite flowers located towards the centre of the head.
Cotyledons elliptic, ovate to broadly spathulate, about 3-4 x 2-3 mm. First pair of leaves ovate on comparatively long slender petioles. Apex rounded and apiculate, base attenuate. Both the upper and lower surfaces sparsely clothed in pale hairs. At the tenth leaf stage: leaves spathulate, base of petiole clasping the stem. All plant parts clothed in erect white hairs.
Distribution and Ecology
An introduced species originally from North America, now naturalized in NEQ and southwards as far as south-eastern Queensland. Altitudinal range in NEQ not known but collected in the 750-1150 m range. Usually grows as a weed of agricultural land but also found in disturbed areas and along roads in rain forest.
Herb (herbaceous or woody, under 1 m tall)
Shrub (woody or herbaceous, 1-6 m tall)