Trifid Bur-marigold

Bidens tripartita

This is a common and widespread annual plant seen from July to September. The dull yellow flowerheads, which are rayless, can measure up to 25mm across and appear singly on erect stems with opposite leaves. Typically, the leaves have three lobes, though there can be instances of five lobes, with the central lobe being the largest. The petioles are short and winged at the base. This particular plant, growing by the Hainault Lake outflow, reached a height of approximately 50cm.