Botanical name: Crotalaria retusa Family: Fabaceae (Pea family)
Rattleweed is an annual herb with erect stem, growing up to 1.3 m tall. Stems are ridged, velvety with short appressed hairs. Leaves are simple, inverted-lance-shaped, 3.3-9.2 cm long, 1-3.8 cm wide. Tip is rounded or occasionally pointed, but mostly with a blunt, notched tip, as the species name retusa indicated. Leaf base is wedge-shaped, with stalks up to 3 mm long. Flowers are 1.7-2.4 cm long, 13-23 in somewhat lax spikes at the end of branches, up to 27 cm long, including the stalk. Sepal tube is 4.5-6.5 mm long, with 5.5-10 mm long sepals. Petals are yellow with fine purple lines near base. Standard petal is 1.4-1.8 cm long, 1.7-2.5 cm wide, wings are oblong-lanceshaped, 1.3-1.5 cm long, 9-11 mm wide, keel petals short, beak twisted, margins hairy. Pods are greenish to start with, dark brown to black at maturity, 3-4 cm long, hairless.
Identification credit: Gurcharan Singh
The flower labeled Rattleweed is ...