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Bransford, W.D. and Dolphia
Helianthus giganteus L.
Synonym(s): Helianthus alienus, Helianthus borealis, Helianthus giganteus ssp. alienus, Helianthus giganteus var. subtuberosus, Helianthus nuttallii var. subtuberosus, Helianthus subtuberosus, Helianthus validus
USDA Symbol: hegi
USDA Native Status: L48 (N), CAN (N)
As the name suggests, giant sunflower is a large, showy plant.A tall, rough, reddish stem bearing several to many light yellow flower heads. The branched, purplish stem grows to 10 ft. tall and bears terminal, yellow flowers.
Despite this plants names, its flower heads are comparatively small; the common and species names actually refer to the plants overall height.
Plant CharacteristicsDuration: Perennial Habit: Herb Flower:
Fruit: Size Class:
Bloom InformationBloom Color: Yellow
Bloom Time: Jul , Aug , Sep
, WV Canada: MB
, SK Native Distribution: NY
& Ont. to MN,
s. to GA
& KY; naturalized northeastward Native Habitat:
Moist places; marshes
Growing ConditionsLight Requirement: Sun
Soil Moisture: Moist , Wet
Soil Description: Moist soils
Conditions Comments: Not Available
BenefitUse Wildlife: Seed heads attract birds.
Warning: The stems and leaves can cause skin irritation in humans. The plant can be fatal to animals if ingested. Humans should generally avoid ingesting plants that are toxic to animals.
Conspicuous Flowers: yes
Excellent germination occurs with seeds that have been refrigerated over winter. Stem
cuttings can be taken before flowering, but the easiest method of increase in to divide the clump in early spring. Seed Collection:
Nutlets usually mature 2-3 weeks after flowering. To beat finched to the seeds, secure a small bag around seeds heads after the flowers fade. Air-dry collected seed heads, separate nutlets from chaff, and store in sealed, refrigerated containers. Seed Treatment:
Not Available Commercially Avail:
National Wetland Indicator Status
This information is derived from the U.S. Army Corps of Engineers National Wetland Plant List, Version 3.1
(Lichvar, R.W. 2013. The National Wetland Plant List: 2013 wetland ratings. Phytoneuron 2013-49: 1-241). Click here
for map of regions.
From the National Organizations Directory
According to the species list provided by Affiliate Organizations, this plant is either on display or available from the following:
Native Seed Network
- Corvallis, OR
Record Last Modified: 2007-01-01
Research By: TWC Staff