Family: Asteraceae Aster Family
Genus: Ambrosia Ragweed
Genus of about 15 species of annual herbs with unisexual flower heads and producing pollen that is one of the chief causes of hay fever. Found mainly in North and South America. Scientific Name: Ambrosia trifida L.
Common Name(s): Giant Ragweed, Great Ragweed, Horse-Cane, Crownweed
Growth Type: annual
Species Description:
Click on the thumbnails to view large image.  | Caption:
ID: Hrb-AMBTR-024
Source: 35mm slide (photo)
Credit:
Keyword(s): inflorescense, leaf, vegetative
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 | Caption:
ID: Hrb-AMBTR-026
Source: 35mm slide (photo)
Credit:
Keyword(s): leaf, vegetative
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 | Caption: Giant ragweed plant growing in a soybean field.
ID: Hrb-AMBTR-013
Source: 35mm slide (photo)
Credit:
Keyword(s): inflorescense, mature
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 | Caption: Giant ragweed seeds with spines located at the top of the seed.
ID: Hrb-AMBTR-015
Source: 35mm slide (photo)
Credit:
Keyword(s): seed
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 | Caption: Giant ragweed seeds with spines located at the top of the seed.
ID: Hrb-AMBTR-016
Source: 35mm slide (photo)
Credit:
Keyword(s): seed
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 | Caption: Giant ragweed seeds.
ID: Hrb-AMBTR-014
Source: 35mm slide (photo)
Credit:
Keyword(s): seed
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 | Caption: Giant ragweed's 3 lobed, opposite leave.
ID: Hrb-AMBTR-011
Source: 35mm slide (photo)
Credit:
Keyword(s): leaf, seedling
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 | Caption: Giant ragweed's 3 lobed, opposite leave.
ID: Hrb-AMBTR-012
Source: 35mm slide (photo)
Credit:
Keyword(s): leaf, seedling
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 | Caption: Giant ragweed's 3-5 lobed leaf and male spike inflorescence at the tip of the stem.
ID: Hrb-AMBTR-021
Source: 35mm slide (photo)
Credit:
Keyword(s): flowering, inflorescense, leaf, mature
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 | Caption: Giant ragweed's 3-5 lobed leaves and female flowers located in the plant's leaf axils.
ID: Hrb-AMBTR-004
Source: 35mm slide (photo)
Credit:
Keyword(s): flowering, inflorescense, leaf, mature
|
 | Caption: Giant ragweed's 3-5 lobed, opposite leaves.
ID: Hrb-AMBTR-005
Source: 35mm slide (photo)
Credit:
Keyword(s): leaf, vegetative
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 | Caption: Giant ragweed's cotyledon's and lobed, hairy leaves.
ID: Hrb-AMBTR-006
Source: 35mm slide (photo)
Credit:
Keyword(s): leaf, seedling
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 | Caption: Giant ragweed's cotyledons and opposite, hairy, deeply lobed leaves.
ID: Hrb-AMBTR-001
Source: 35mm slide (photo)
Credit:
Keyword(s): leaf, seedling
|
 | Caption: Giant ragweed's cotyledons and opposite, lobed leaves.
ID: Hrb-AMBTR-007
Source: 35mm slide (photo)
Credit:
Keyword(s): leaf, seedling
|
 | Caption: Giant ragweed's cotyledons and opposite, lobed leaves.
ID: Hrb-AMBTR-008
Source: 35mm slide (photo)
Credit:
Keyword(s): leaf, seedling
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 | Caption: Giant ragweed's large, 3-5 lobed leaves.
ID: Hrb-AMBTR-019
Source: 35mm slide (photo)
Credit:
Keyword(s): leaf, vegetative
|
 | Caption: Giant ragweed's large, 3-5 lobed leaves.
ID: Hrb-AMBTR-022
Source: 35mm slide (photo)
Credit:
Keyword(s): leaf, vegetative
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 | Caption: Giant ragweed's male inflorescence at the tip of each stem and female inflorescence in the leaf axils.
ID: Hrb-AMBTR-017
Source: 35mm slide (photo)
Credit:
Keyword(s): flowering, inflorescense, mature
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 | Caption: Giant ragweed's male spike inflorescence at the tip of hairy stem.
ID: Hrb-AMBTR-018
Source: 35mm slide (photo)
Credit:
Keyword(s): inflorescense, mature, stem
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 | Caption: Giant ragweed's opposite, lobed leaves.
ID: Hrb-AMBTR-009
Source: 35mm slide (photo)
Credit:
Keyword(s): leaf, seedling
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 | Caption: Giant ragweed's spiked male inflorescence at the tip of the branches and hairy deeply lobed leaves.
ID: Hrb-AMBTR-003
Source: 35mm slide (photo)
Credit:
Keyword(s): flowering, inflorescense, mature
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 | Caption: Giant ragweed's tall growth habit.
ID: Hrb-AMBTR-002
Source: 35mm slide (photo)
Credit:
Keyword(s): mature
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 | Caption: Illustration depicting giant ragweed seedling and mature plant.
ID: Hrb-AMBTR-020
Source: 35mm slide (illustration)
Credit:
Keyword(s): flowering, inflorescense, leaf, mature, seedling
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 | Caption: Illustration depicting giant ragweed's cotyledons and hairy, lobed, opposite leaves.
ID: Hrb-AMBTR-010
Source: 35mm slide (illustration)
Credit:
Keyword(s): leaf, seedling
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