Helianthus strumosus

Native

Dry to moderate moisture. Bottomland forests, upland forests, stream banks, river banks, railroads, roadsides. Full to partial sun.

July to October

Yellow ray florets, yellow disk florets

24″ to 72″

This is a 24″ to 72″ tall, erect, perennial forb that rises from a long-creeping rhizome. The rhizome is branched and has tubers at the tips of the branches. It usually forms dense colonies.

The stems are erect and usually solitary, though they sometimes appear in small clumps. They are hairless or sparsely hairy below the inflorescence and are often somewhat covered with a whitish, waxy coating (glaucous).

There are usually 8 to 20 pairs of opposite leaves. Sometimes the leaves near the top of the stem are alternate. The larger leaves are on ⅜″ to 1⅛″ long leaf stalks The leaf blades are relatively thick, firm, lance-shaped to narrowly egg-shaped, and flat, not folded longitudinally. They are 2¾″ to 7″ long and ¾″ to 4″ wide, 2 to 5 times as long as wide. They are wedge-shaped to almost heart-shaped at the base, and taper to a sharp point at the tip with slightly convex sides along the tip. The upper surface is rough with minute hairs that have a small bump at their base. The lower surface is usually sparsely to densely hairy with soft hairs, but may be hairless or almost hairless and pale green to silvery. The margins are shallowly toothed to untoothed. The leaves have 3 main veins, a midvein and a pair of lateral veins that branch off the main vein just above the base and arch upward. There are also several less prominent lateral veins.

The inflorescence is 3 to 15 flower heads appearing as a single head at the end of the stem and few-headed clusters from the upper leaf axils.

The flower heads are 1½″ to 4″ wide. There are 8 to 15 yellow ray florets and 35 or more yellow disk florets. The tips of the bracts that form the involucre spread outwards.

The fruit is an achene.

Woodland sunflower (Helianthus divaricatus) leaves are stalkless or on leaf stalks less than 3 ⁄16″ long. It does not occur in Minnesota.