Ditches, floodplains, marshes, ponds, riversides, swamps, water, waterside, wetland.
Golden yellow, oval petals. The tips of the petals are either notched or pointed. Flowers have 5 stamens. The inner bracts are blunt and pale yellow. The green outer bracts of the flowers are long, narrow and curly. The flowers nod with age. The flowers are larger than those of the similar looking Trifid Bur-marigold (Bidens tripartita).
A dark brown, 4-angled seed, 6 to 8mm in length. The tip of the seed has 3 or 4 barbed awns attached to it. The fruits are narrower than those of Trifid Bur-marigold.
The leaves are narrow, measuring up to 6 inches (15cm) long and 1 inch (2.5cm) wide. They are stalkless and hairless. The leaves are opposite and clasp the stem. Leaf margins have some but few large teeth. The stem is often tinged purple. The stem is thicker than that of Trifid Bur-marigold. Nodding Bur-marigold is an annual.