Quercus rubra Linnaeus var. ambigua (A. Gray) Fernald. Subgenus: Quercus. Section: Lobatae. Subsection: Coccineae. Gray Oak. Phen: May; Sep-Oct (of the second year). Hab: Forests on ridges, slopes, and coves, in the Southern Appalachians mostly at over 1000 meters elevation. Dist: Fairly widespread in ne. North America south to PA, and in the Appalachians to w. NC, nw. SC, and n. GA.

Origin/Endemic status: Native

Other Comments: This and var. rubra tend to intergrade and their distinction as even varieties may not be warranted. For discussion of the two varieties, see McDougal & Parks (1984) and Jensen (1977).

Synonymy: = K1, Mi; = Quercus borealis F.Michx. – S; = Quercus borealis F.Michx. var. borealis – G, GrPl; = Quercus rubra L. var. borealis (F.Michx.) Farw. – F, FNA3, RAB, WV; < Quercus rubra L. – C, Il, K3, K4, NE, NY, Pa, S13, Tat, Tn, Va, W

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Wetland Indicator Status:

• Eastern Mountains and Piedmont: FACU (taxonomic split from wetland indicator species)
• Great Plains: FACU (taxonomic split from wetland indicator species)
• Midwest: FACU (taxonomic split from wetland indicator species)
• Northcentral & Northeast: FACU (taxonomic split from wetland indicator species)

Heliophily: 4