SPECIES: Toxicodendron radicans, T. rydbergii

Table of Contents


Image 2: Western poison-ivy. Photo courtesy of Dave Powell, USDA Forest Service, Bugwood.org.

Image 1: Eastern poison-ivy. Photo courtesy of David J. Moorhead, University of Georgia, Bugwood.org.  

Innes, Robin J. 2012. Toxicodendron radicans, T. rydbergii. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/ [].


poison ivy

for Toxicodendron radicans:
eastern poison-ivy
common poison-ivy

for Toxicodendron rydbergii:
western poison-ivy
Rydberg's poison-ivy

The genus name for poison-ivy is Toxicodendron Mill. (Anacardiaceae). This review summarizes information on the following poison-ivy taxa:

Toxicodendron radicans (L.) Kuntze, eastern poison-ivy [40,87,88,92,124,137,168,266,281,283].
Toxicodendron rydbergii (Small ex. Rydb.) Greene, western poison-ivy [29,38,47,83,132,156,240,263].

Nine subspecies of eastern poison ivy are recognized globally, 6 of which occur in the United States:

Toxicodendron radicans subsp. radicans (L.) Kuntze [55,88,132,156,247,283]
Toxicodendron radicans subsp. divaricatum (Greene) Gillis [83,263]
Toxicodendron radicans subsp. eximium (Greene) Gillis [55,132,202,263]
Toxicodendron radicans subsp. negundo (Greene) Gillis [55,92,132,240,263,268,283]
Toxicodendron radicans subsp. pubens (Engelm. ex Watson) [55,263,283]
Toxicodendron radicans subsp. verrucosum (Scheele) Gillis [55,83,92,132,263]

Eastern and western poison-ivy are morphologically plastic [81] and intergrade with one another [83,87,171]. They occasionally hybridize where their ranges overlap [47,83,92,268]. Eastern poison-ivy may hybridize with Atlantic poison-oak (T. pubescens), and western poison-ivy may hybridize with Pacific poison-oak (T. diversilobum) [83].

Older literature often does not distinguish between eastern and western poison-ivy, and because the 2 species' geographic distributions overlap, it is sometimes impossible to determine to which species older literature is referring. In this review, species are referred to by their common names, when possible, and "poison-ivies" refers to both species.

for Toxicodendron radicans subsp. radicans:
Toxicodendron radicans (L.) Kuntze var. radicans [87,268]
Toxicodendron radicans var. littoralis (Mearns) F. A. Barkley [266]
Rhus littoralis Mearns [282]
Rhus radicans L. [40,88,137,156,168,204,243,244,281,282]
Rhus radicans var. littoralis (Mearns) Deam [132,282]
Rhus toxicodendron var. radicans (L.) Dippel [223]

for Toxicodendron radicans subsp. divaricatum (Greene) Gillis:
Toxicodendron radicans var. divaricatum (Greene) F. A. Barkley [83,133]
Toxicodendron divaricatum Greene [83,133]
Rhus radicans var. divaricata (Greene) Fern. [83,278]

for Toxicodendron radicans subsp. eximium (Greene) Gillis:
Toxicodendron radicans var. eximia (Greene) F. A. Barkley [83,202,266]
Toxicodendron eximium Greene [83,202]
Rhus eximium (Greene) Standl. [202]
Rhus eximia (Greene) Standl. [83]
Rhus toxicodendron var. eximia (Greene) McNair [83,132]

for Toxicodendron radicans subsp. negundo (Greene) Gillis:
Toxicodendron radicans var. negundo (Greene) Reveal [55,87,132,230,283]
Toxicodendron radicans var. vulgaris forma negundo (Greene) Fern. [266]
Toxicodendron negundo Greene [223,240,283]
Rhus radicans var. vulgaris (Michaux) de Candolle forma negundo (Greene) Fern. [79,204,240,243,244]
Rhus toxicodendron subsp. negundo (Greene) Gates [240]

for Toxicodendron radicans subsp. pubens (Engelm. ex Watson):
Toxicodendron radicans subsp. pubens (Engelm.) Gillis [92]
Toxicodendron radicans subsp. pubens (Engelm. ex Watson) Gillis [132]
Toxicodendron radicans var. pubens (Engelm. ex Watson) Reveal [132,283]
Rhus toxicodendron var. pubens Engelm. ex Watson [283]

for Toxicodendron radicans subsp. verrucosum (Scheele) Gillis:
Toxicodendron radicans var. verrucosa (Scheele) F. A. Barkley [266]
Toxicodendron radicans var. verrucosum (Scheele) F. A. Barkley [83,132]
Toxicodendron verrucosum (Scheele) Greene [83]
Rhus radicans var. verrucosa (Scheele) Fern. [83]
Rhus verricosa Scheele [83,132]

for Toxicodendron rydbergii (Small ex Rydb.) Greene:
Toxicodendron rydbergii (Small) Greene [87,92,274,275]
Toxicodendron radicans var. rydbergii (Small ex Rydb.) Erskine [47,83,132,263]
Toxicodendron radicans var. rydbergii (Small) Erskine [274,275]
Toxicodendron radicans var. rydbergii (Small) Rehd. [266]
Toxicodendron longipes Greene [47,83,274,275]
Toxicodendron desertorum Lunell [83,92,132,240,263]
Rhus rydbergii Small ex Rydb. [47,83,275]
Rhus rydbergii Small [223]
Rhus radicans var. rydbergii (Small) Rydb. [156,214,223,244,268,275]
Rhus radicans var. rydbergii (Small) Rehd. [79,133]
Rhus radicans var. rydbergii (Small ex Rydb.) Rehd. [47,83,132]
Rhus radicans var. vulgaris (Michaux) de Condolle [132,263]
Rhus toxicodendron var. rydbergii (Small) Garrett [223,274,275]
Rhus toxicodendron var. rydbergii (Small ex Rydb.) Rehd. [263]
Rhus toxicodendron var. rydbergii (Small ex Rydb.) Garrett [83]
Rhus toxicodendron var. vulgaris (Michaux) [132,263]

for Toxicodendron radicans:

for Toxicodendron rydbergii:

Complete FEIS review for Toxicodendron radicans, T. rydbergii

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