Helianthus divaricatus L. -

Family - Asteraceae
Stems - Thin erect, simple, herbaceous, typically single from the base, from a long horizontal rhizome, typically purplish and somewhat glaucous, mostly glabrous but with a few pustulate based hairs directly below the nodes, terete, 2-4mm in diameter at the base, -1m tall, with +/-10 nodes below the flowers.
Root.

Leaves - Opposite, decussate, sessile or very-short