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Montana Field Guide

Montana Field Guides

Giant Ragweed - Ambrosia trifida

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Native Species

Global Rank: G5
State Rank: SNR
C-value: 2


Agency Status
USFWS:
USFS:
BLM:


 

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General Description
Taprooted annual. Stems erect, simple or branched, 30–150 cm, strigose to hispid. Leaves opposite; blade lanceolate to broadly ovate, 4–15 cm long, serrate, often 3-lobed, hispid, glandular. Female heads 1-flowered. Male heads saucer-shaped, black-veined, 2–4 mm wide, villous, hispid, glandular with 3 to 25 florets, nodding on peduncles 1–3 mm long. Bur 3–5 mm long, deltoid, ribbed, glabrous with ca. 5 erect spines (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Range Comments
Roadsides, fields, streambanks; plains, valleys (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Observations in Montana Natural Heritage Program Database
Number of Observations: 21

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density

Recency

 

(Observations spanning multiple months or years are excluded from time charts)



Habitat

References
  • Literature Cited AboveLegend:   View Online Publication
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
  • Additional ReferencesLegend:   View Online Publication
    Do you know of a citation we're missing?
    • Eggers, M.J.S. 2005. Riparian vegetation of the Montana Yellowstone and cattle grazing impacts thereon. M.Sc. Thesis. Montana State University, Bozeman, MT. 125 p.
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2022. Manual of Montana Vascular Plants, Second Edition. Fort Worth, TX: BRIT Press. viii + 779 p.
  • Web Search Engines for Articles on "Giant Ragweed"
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Citation for data on this website:
Giant Ragweed — Ambrosia trifida.  Montana Field Guide.  .  Retrieved on , from