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Aquatic and Wetland Vascular Plants of the Northern Great Plains

Helianthus L. -- Sunflower


Stout perennials (those included here) with a stout rootstock and thick tuberous roots; stem simple or branched above. Leaves simple, petiolate, usually opposite below and alternate above, but sometimes all opposite, or opposite and alternate mixed over the length of the stem, the blades narrowly lanceolate to ovate-lanceolate, entire or serrate. Heads 1-several (seldom many), terminal on the main stem and lateral branches, conspicuously radiate; involucre of several series of narrow, overlapping bracts; receptacle flat to convex, chaffy, the chaffy bracts clasping the achenes (ovaries) of the disk florets; ray florets usually 10-20, sterile, the ligules yellow, spreading; disk florets numerous, perfect, their corollas yellow. Achenes flattened, narrowly obovate; pappus of 2 deciduous, awn-tipped scales.

References:

Heiser, C. B.  1969.  The North American sunflowers (Helianthus).
     Mem.  Torrey Bot. Club 22:1-218.

Long, R. W.  1966. Biosystematics of the Helianthus nuttallii
     complex.  Brittonia 18:64-79.

Lead Characteristic Go To
1 Leaves coarsely serrate, often more than 4 cm wide; stem glabrous in the middle and lower portions. H. grosseserratus
1 Leaves entire to shallowly dentate, less than 4 cm wide; stem glabrous to hispid in the middle and lower portions. H. nuttallii


49. Asteraceae, the Aster Family
12. Helianthus L. -- Sunflower
1. Helianthus grosseserratus Martens -- Sawtooth sunflower
2. Helianthus nuttallii T. & G. -- Nuttall's sunflower


Return to Family -- Asteraceae - The Aster Family
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