College of Food, Agricultural and Natural Resource Sciences

Strand Memorial Herbarium

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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.

plant imageCaption: plant image

ID: Hrb-AMBTR-024
Source: 35mm slide (photo)
Credit:
Keyword(s): inflorescense, leaf, vegetative
plant imageCaption: plant image

ID: Hrb-AMBTR-026
Source: 35mm slide (photo)
Credit:
Keyword(s): leaf, vegetative
Giant ragweed plant growing in a soybean field.Caption: Giant ragweed plant growing in a soybean field.

ID: Hrb-AMBTR-013
Source: 35mm slide (photo)
Credit:
Keyword(s): inflorescense, mature
Giant ragweed seeds with spines located at the top of the seed.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
Giant ragweed seeds with spines located at the top of the seed.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
Giant ragweed seeds.Caption: Giant ragweed seeds.

ID: Hrb-AMBTR-014
Source: 35mm slide (photo)
Credit:
Keyword(s): seed
Giant ragweed's 3 lobed, opposite leave.Caption: Giant ragweed's 3 lobed, opposite leave.

ID: Hrb-AMBTR-011
Source: 35mm slide (photo)
Credit:
Keyword(s): leaf, seedling
Giant ragweed's 3 lobed, opposite leave.Caption: Giant ragweed's 3 lobed, opposite leave.

ID: Hrb-AMBTR-012
Source: 35mm slide (photo)
Credit:
Keyword(s): leaf, seedling
Giant ragweed's 3-5 lobed leaf and male spike inflorescence at the tip of the stem.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
Giant ragweed's 3-5 lobed leaves and female flowers located in the plant's leaf axils.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
Giant ragweed's 3-5 lobed, opposite leaves.Caption: Giant ragweed's 3-5 lobed, opposite leaves.

ID: Hrb-AMBTR-005
Source: 35mm slide (photo)
Credit:
Keyword(s): leaf, vegetative
Giant ragweed's cotyledon's and lobed, hairy leaves.Caption: Giant ragweed's cotyledon's and lobed, hairy leaves.

ID: Hrb-AMBTR-006
Source: 35mm slide (photo)
Credit:
Keyword(s): leaf, seedling
Giant ragweed's cotyledons and opposite, hairy, deeply lobed leaves.Caption: Giant ragweed's cotyledons and opposite, hairy, deeply lobed leaves.

ID: Hrb-AMBTR-001
Source: 35mm slide (photo)
Credit:
Keyword(s): leaf, seedling
Giant ragweed's cotyledons and opposite, lobed leaves.Caption: Giant ragweed's cotyledons and opposite, lobed leaves.

ID: Hrb-AMBTR-007
Source: 35mm slide (photo)
Credit:
Keyword(s): leaf, seedling
Giant ragweed's cotyledons and opposite, lobed leaves.Caption: Giant ragweed's cotyledons and opposite, lobed leaves.

ID: Hrb-AMBTR-008
Source: 35mm slide (photo)
Credit:
Keyword(s): leaf, seedling
Giant ragweed's large, 3-5 lobed leaves.Caption: Giant ragweed's large, 3-5 lobed leaves.

ID: Hrb-AMBTR-019
Source: 35mm slide (photo)
Credit:
Keyword(s): leaf, vegetative
Giant ragweed's large, 3-5 lobed leaves.Caption: Giant ragweed's large, 3-5 lobed leaves.

ID: Hrb-AMBTR-022
Source: 35mm slide (photo)
Credit:
Keyword(s): leaf, vegetative
Giant ragweed's male inflorescence at the tip of each stem and female inflorescence in the leaf axils.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
Giant ragweed's male spike inflorescence at the tip of hairy stem.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
Giant ragweed's opposite, lobed leaves.Caption: Giant ragweed's opposite, lobed leaves.

ID: Hrb-AMBTR-009
Source: 35mm slide (photo)
Credit:
Keyword(s): leaf, seedling
Giant ragweed's spiked male inflorescence at the tip of the branches and hairy deeply lobed leaves.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
Giant ragweed's tall growth habit.Caption: Giant ragweed's tall growth habit.

ID: Hrb-AMBTR-002
Source: 35mm slide (photo)
Credit:
Keyword(s): mature
Illustration depicting giant ragweed seedling and mature plant.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
Illustration depicting giant ragweed's cotyledons and hairy, lobed, opposite leaves.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