Helianthus petiolaris ssp. petiolaris

Native

Dry. Prairies, bluff tops, railroads, roadsides, and open, disturbed areas. Full sun. Sandy soil.

June to September

Yellow ray florets, reddish-brown to purple disk florets

16″ to 40″

This is an erect, annual forb that rises on a single stem from a taproot. It can be from 16″ to 78″ tall, though in Minnesota it is seldom more than 40″ in height.

The stems are erect, relatively stout, and moderately covered with short, stiff, ascending hairs.

There are usually 8 to 25 alternate leaves. Sometimes the leaves near the base of the stem are opposite. The larger leaves are leaf stalks that are usually ¾″ to 1½″ long, but may be as much as 4″ long.

The leaf blades are lance-shaped to triangular 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 slightly heart-shaped, wedge-shaped, or squared off at the base, and taper to a sharp point at the tip. The upper surface is usually green, sometimes bluish-green, and rough to the touch with minute, straight, appressed hairs. The lower surface is similar, but may also be sparsely covered with yellow glands. The margins are untoothed or finely, irregularly toothed. The leaves have 3 main veins, a midvein and a pair of lateral veins that branch off the main vein at the base of the blade and arch upward.

The inflorescence is rarely a solitary head, usually an open, branched cluster of 2 to 5 flower heads at the end of the stem. The flower heads are on stalks that are 1½″ to 6″ long or longer. The stalks usually do not have a leafy bract subtending the flower head.

The whorl of bracts at the base of the flower head (involucre) is ⅜″ to 1″ in diameter. The bracts of the involucre are lance-shaped to narrowly egg-shaped and taper to a sharply-pointed tip. The tips of the bracts are sometimes loosely ascending, but more often are spreading and then curved upwards at the tip.

The flower heads are 1½″ to 2½″ wide, the disk is ⅜″ to 1″ in diameter. There are 10 to 30 yellow ray florets and 50 to 100 or more reddish-brown to purple disk florets.

The fruit is an achene.

See the Sunflowers ID Filter for a spreadsheet to aid identification of this and similar species.