Bur-marigold, Bidens laevis
The Bur-marigold (Bidens laevis) is a member of the daisy family also known as Smooth Meggarticks. It is a species of flowering plant native to the southern half of the United States, where it thrives in wetlands, including estuaries and riverbanks. It looks comparable to its relative Bidens cernua and the two are often mistaken for each other. The plant is a perennial herb that grows to heights between 8 inches to sometimes 2 yards. The narrow lance-shaped leaves have finely toothed edges and sharp tips. Each leaf is between 2 and 6 inches long. The inflorescence bears one or more flower heads which bend down with the weight of the fruit after flowering. In the center of each head are yellow disc florets and a fringe of 7 or 8 yellow ray florets each up to an inch long. It produces sharply barbed achene fruit.