Flower:

Flowers are at the end of branching stems at the top of the plant. Individual flowers are 2½ to 4 inches across with 10 to 20 ray flowers (petals) and yellow center disk flowers.

There are a few layers of bracts behind the flower; bracts are narrow, sharply pointed and spreading with fine hairs around the edges especially near the base of a bract.

Leaves and stem:

Leaves are up to 8 inches long and 2½ inches wide, coarsely toothed, pointed at the tip, tapering at the base, on a stalk up to 1½ inches long. The texture is rough. Leaves are mostly oppositely attached but are alternate in the upper part of the plant; they tend to fold up along the center vein, and may be arching. The stem is hairless and green or purplish with a white bloom like seen on a plum (see more photos below).

Fruit:

The center disk forms a head of dry seed each about 1/8 inch long and without a tuft of hair, but with 2 somewhat bristly scales at the top.

Notes:

Sawtooth Sunflower is similar to Giant Sunflower (Helianthus giganteus) and Maximilian Sunflower (Helianthus maximiliani). Giant Sunflower has a distinctly hairy stem and its leaves are stalkless or nearly so, whereas Sawtooth Sunflower has a hairless stem, often with a whitish bloom, and longer leaf stalks. Maximilian Sunflower has leaves that also fold up and arc like Sawtooth Sunflower, but they are mostly toothless with shorter stalks. In the location where many of these photos were taken, a number of plants had galls of various sizes on the stems near leaf joints (see leaf photo above, and photo below). One reference mentions that a species of weevil is a possible resident.