Search Field Guide
Advanced Search
MT Gov Logo
Montana Field Guide

Montana Field Guides

Giant Ragweed - Ambrosia trifida

No photos are currently available
If you have a high quality photo of this species, are confident in the identification, and would like to submit it for inclusion on the Montana Field Guide, please send it to us using our online photo submission tool.


Image Copyright and Usage Information
Native Species

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


Agency Status
USFWS:
USFS:
BLM:


 

External Links

 
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"
Login Logout

Take us with you! PDF icon

Look for this PDF icon as you search and browse.  Click it to build a custom PDF with species shown on that page or for all the species within that taxonomic level.  To create your own list of species, use the PDF Creator tool at the bottom of the Advanced Search page.

Here's some links if you want to download a whole group.

Mammals
Birds
Reptiles
Amphibians
Fish
Invertebrates
Butterflies / Moths
Dragonflies / Damselflies
Ferns and allies
Conifers
Flowering Plants (Dicots)
Flowering Plants (Monocots)
Bryophytes
Lichens
Ecological Systems
Noxious Weeds
Citation for data on this website:
Giant Ragweed — Ambrosia trifida.  Montana Field Guide.  .  Retrieved on , from