STIFF SUNFLOWER
Helianthus pauciflorus
SUNFLOWER FAMILY (Asteraceae)
Identification
- Flowering time - August, September
- Rare - single small "colony" in NW prairie
- Grows in colonies
- Dark central disk (usually)
- Narrow leaves separate it from Annual Sunflower (see Comments)
This native erect perennial grows up to 8 feet tall with rough, green to reddish stems. Plants arise from underground stems (rhizomes) which may form fairly extensive and characteristic “colonies” (D). The narrow, stiff, lance-shaped leaves are from 2-8 inches long by 1-2 inches wide and very rough to the touch (C). Lower leaves are opposite with short leaf stalks while upper ones are often alternate and much reduced in size. Long stalks bear one to several 2-3 inch flower heads with 10-20 petal-like ray florets surrounding the reddish-purple (sometimes yellow) disk florets (A,B).
Found on drier upland prairie sites, flowering in August and September. At Neale Woods it is rare in Knull Prairie where a single small colony exists which appears to be declining in vigor each year.
Sunflowers with flat disks (“flatheads”) are often confusing, and Stiff Sunflower may be the most confusing of all with two recognized subspecies as well as hybrids to contend with! There are exceptions, but most Stiff Sunflowers have dark disks separating them from all of our “flatheads” but the Common Sunflower (Helianthus annuus). The narrow leaves of Stiff Sunflower are very different from Common Sunflower’s broad, heart-shaped leaves.
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