Helianthus giganteus L.  
Family: Asteraceae
giant sunflower, swamp sunflower, tall sunflower
[Helianthus alienus E.Watson, Helianthus borealis E.Watson, Helianthus exasperatus E.Watson, Helianthus giganteus subsp. alienus L., Helianthus giganteus var. subtuberosus L., Helianthus membranaceus E.Watson, Helianthus nuttallii var. subtuberosus Torr. & A.Gray, Helianthus subtuberosus (Britton) Britton, Helianthus validus E.Watson]
Helianthus giganteus image
Merel R. Black  
Etymology: Helianthus: derived from two Greek words helios, "sun," and anthos, "flower," in reference to the sunflower's supposed tendency to always turn toward the sun
Plants: erect, perennial, 3'-10' tall forb; stems usually with spreading hairs but sometimes hairless, often purplish
Leaves: opposite on the lower stem, upper alternate, flat, narrow, at least 3 times as long as wide, upper surface rough, lower with long hairsleaf drawing
Flowers: head 1 3/4"- 3 1/4" wide with 10-20 yellow rays, yellow disks, hairy bracts (phyllaries) long and loose; inflorescence in loose clusters of several to many heads on stalks less than 4" long; blooms July-Oct.
Habitat: moist; forests, swamps
Helianthus giganteus image
Merel R. Black  
Helianthus giganteus image
Merel R. Black  
Helianthus giganteus image
Janice Stiefel  
Helianthus giganteus image
Matthew L. Wagner  
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