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Montana Field Guide

Montana Field Guides

Western Poison-ivy - Toxicodendron rydbergii
Other Names:  Rhus radicans, Toxicodendron radicans var. rydbergii, Rhus toxicodendron


Global Rank: G5
State Rank: S5

Agency Status
USFWS:
USFS:
BLM:
MNPS Threat Rank:
C-value: 4

External Links






 
General Description
Rhizomatous subshrub, shrub, or (rarely) vine. Stems erect, 10–50 cm, pubescent, branched and bearing leaves above. Herbage glabrous, sparsely pubescent on veins, allergenic. Leaves trifoliate, long-petiolate; leaflets ovate, remotely serrate to entire, 2–12 cm long, shiny above; lateral leaflets asymmetrical. Inflorescence an axillary, few-branched panicle. Flowers white; petals 2–3 mm long, dark-veined. Drupes crowded, globose, greenish-yellow, 4–6 mm long (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Species Range
Present
 


Range Comments
Much of temperate N. America (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Summary of Observations Submitted for Montana
Number of Observations: 27

(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
Streambanks, woodlands, open forest; plains, valleys (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

References
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Citation for data on this website:
Western Poison-ivy — Toxicodendron rydbergii.  Montana Field Guide.  .  Retrieved on , from