Chokeweeds (the name I grew up with) growing wild in Kentucky.
Actual name: Helianthus strumosus- Woodland Sunflower
Woodland Sunflower (Helianthus divaricatus)
Description: This perennial wildflower is 2½-6’ tall with a central stem that becomes branched where the flowerheads occur. This stem is light green to dark purple, slender, terete (round in cross-section), glabrous to sparsely covered with short stiff hairs, and sometimes glaucous. Upper secondary stems have similar characteristics. Pairs of widely spreading opposite leaves occur along the central stem and any secondary stems; each pair of leaves rotates 90° from the pair of leaves below. Leaf blades are 2-6" long and ½-2" across; they are lanceolate-oblong to ovate-oblong in shape, and either toothless or with widely spaced teeth along their short-ciliate margins. The base of each leaf blade is rounded-truncate, while its tip is long and gradually tapering. The upper surface of the leaf blades is yellowish green to medium green and sparsely to moderately covered with short stiff hairs.
The blooming period occurs from mid-summer to early fall for about 2 months.