Overwintering, annual seed-propagated weed. Prefers high-nitrogen sandy, sandy loam and loamy soils and is capable of surviving dry periods. The plants probably grew wild from a botanical garden in France after 1685.
Horseweed [Conyza canadensis]
Cotyledons are oval, narrower at the petiole (Picture 1). The first leaves have a pronounced petiole, ovate. The later leaves are linear-oblanceolate (rounded apex and tapered base), with short hairs, the middle and upper leaves are stalkless (Picture 3). The flower heads are very numerous but small and inconspicuous (Picture 3), closely grouped in a terminal panicle. The flowers are yellowish-white to reddish-white (Picture 4). The seeds are 1 mm long