Giant Sunflower (Helianthus giganteus): yellow Minnesota wildflowers

Giant Sunflower

Plant Info
Also known as:	Tall Sunflower, Swamp Sunflower
Scientific name:	Helianthus giganteus
Family:	Aster (Asteraceae)
Life cycle:	perennial
Origin:	native
Habitat:	sun; moist woods, marshes, swamps
Bloom season:	summer
Plant height:	4 to 10 feet
USDA PLANTS database:	Minnesota county distribution map
Spotted in Ramsey County at:	Long Lake Regional Park Rice Creek Trail Corridor Vadnais/Snail Lake Regional Park

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Flower:: Flowers are about 2 to 3 inches across, 10 to 20 petals (ray flowers). The petals are bright to golden yellow; the center is a darker yellow. There are several to many flowers branching off at the top of the plant, each at the end of a stalk less than 4 inches long.
The bracts are long, narrow, loose and hairy.
Leaves and stem:: Leaves are up to 7 inches long and 2 inches wide, with little or no leaf stem. The texture of the upper side is very rough but the underside is more softly hairy. The edges are finely to coarsly toothed. Attachment is mostly alternate, but the lower leaves may be oppositely attached. The main stem is thick, hairy, and usually reddish or purple.
Notes:: Giant Sunflower and Sawtooth Sunflower are very similar. Sawtooth Sunflower has a smooth stem that has a white tint, whereas Giant Sunflower has a hairy red stem and hairier leaves. Jerusalem Artichoke is another tall sunflower, but has wider bracts and wider, more finely toothed leaves.

More yellow wildflowers. Photos taken at Pioneer Park, Blaine, MN, July-August 2008

Have you seen this plant in Ramsey County, or have any other comments about it?