Helianthus grosseserratus (Sawtooth Sunflower)
|Also known as:|
|Habitat:||sun; moist fields, prairies, ditches, roadsides|
|Bloom season:||July - October|
|Plant height:||2 to 10 feet|
|Wetland Indicator Status:||GP: FACW MW: FACW NCNE: FACW|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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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).
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.
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.
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- Sawtooth Sunflower plants, about 7 feet tall
- purple stem, and galls
- roadside Sawtooth Sunflower
- garden-grown Sawtooth Sunflower
Photos by K. Chayka taken at Rice Creek Trail Corridor, Ramsey County. Other photos courtesy Peter M. Dziuk.
Have you seen this plant in Minnesota, or have any other comments about it?