selected vouchers: WTU
Notes: The classification of Hedera is disputed, here we follow the taxonomy of Stace (1997). A weed in western Washington, but not as abundant as subsp. hibernica (Murai 1999; Jacobson 2001).
» AJ = Jacobson, A. L. 2001. Wild Plants of Greater Seattle. Publ. by the author, Seattle. 494 pp.
» Murai, M. 1999. Understanding the invasion of Pacific Northwest forests by English ivy (Hedera spp., Araliaceae). Unpublished M. S. thesis, College of Forest Resources, University of Washington, Seattle.
» Stace 1997 = Stace, C. 1997. New Flora of the British Isles. Second Edition. Cambridge University Press, Cambridge, UK. 1130 p.