Flora of the Southeastern United States

Thuja occidentalis Linnaeus. Common name: American Arborvitae, Northern White Cedar, Flat Cedar. Phenology: Mar-Apr. Habitat: Dry limestone, dolostone, and calcareous sandstone cliffs, talus, and boulderfields, also planted and persisting around old homesites and cemeteries (mainly in the Mountains). Rarely (in our area) in calcareous swamps; this is more characteristic in the broader Great Lakes region where this species can be found abundantly within rich swampy hummocks of alkaline fens as well as in drier, thinner soils of Great Lakes alvars. Distribution: Nova Scotia, Hudson Bay, and Manitoba south to Pennsylvania (where considered strictly introduced by Rhoads & Block 2007), Ohio, n. Indiana, n. Illinois, and in the mountains to West Virginia, w. Virginia, and e. Tennessee. This species has been alleged by various authors to have occurred as a native species in nw. North Carolina on limestone bluffs in Alleghany, Ashe, and/or Burke counties, but it has not been relocated in this century, and little apparently suitable habitat occurs in North Carolina.

Origin/Endemic status: Native

Taxonomy Comments: Thuja occidentalis is apparently sister to Thuja koraiensis Nakai of e. Asia, from which it diverged about 20 MYA (Li et al. 2022).

Synonymy ⓘ: = AqW, C, Can, F, FNA2, G, Il, K1, K4, Mi, NS, NY, Pa, POWO, RAB, S, S13, Tn, Va, W, WV, Li et al (2021). Basionym: Thuja occidentalis L. 1753

Links to other floras: = Thuja occidentalis - FNA2

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Wetland Indicator Status:

• Atlantic and Gulf Coastal Plain: FACW
• Eastern Mountains and Piedmont: FACW
• Great Plains: FACW
• Midwest: FACW
• Northcentral & Northeast: FACW

Heliophily ⓘ: 7