Helianthus giganteus (Giant Sunflower)
|Also known as:||Tall Sunflower, Swamp Sunflower|
|Habitat:||sun; moist woods, marshes, swamps|
|Bloom season:||July - September|
|Plant height:||4 to 10 feet|
|USDA PLANTS database:||Minnesota county distribution map|
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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.
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.
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Photos taken at Pioneer Park, Blaine, MN, July-August 2008
Have you seen this plant in Minnesota, or have any other comments about it?