Vascular Plants of North Carolina
Account for Foxglove Beardtongue - Penstemon digitalis   Nuttall ex Sims
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Section 6 » Order Scrophulariales » Family Plantaginaceae
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AuthorNuttall ex Sims
DistributionScattered over the mountains, but of uncertain provenance. Weakley (2018) considers this species to be native in TN and in the VA mountains and Piedmont, but uncertain for NC. The website editors have thus considered the specimen records for the mountains and the adjacent McDowell County (Piedmont) to be of Uncertain Provenance, but those from far downstate to likely be Not Natural.

This species is native mostly to the north and west of NC, ranging from eastern Canada and MN south to central VA, and then southwest to AL and eastern TX.
AbundanceRare in the central mountains and adjacent Piedmont, from McDowell and Madison counties to Haywood and Graham counites, but very rare in the northern mountains and maybe the far southwestern counties. Very rare to absent farther eastward, at least of natural occurrences. The NCNHP considers it as not native, but the website editors are "on the fence" about it being native or not, and thus have given a State Rank of SU (Undetermined), and a Watch List status but as W4 (uncertain whether native or not).
HabitatThis is a species of various open to semi-open habitats, usually somewhat moist -- such as wet meadows and prairies (farther west). Some of the mountain records are from road banks, but some are apparently from moist fields or poorly-drained meadows. Whereas the other "perhaps native" white-flowered beardtongue -- P. pallidus -- grows in dry and glade-like or other high pH barrens, this species favors somewhat moist sites, over acidic (or at least not high pH) soils.
PhenologyBlooms from May to June, and fruits shortly after flowering.
IdentificationThis is medium-height to tall species, growing to about 3' tall (generally the tallest of the genus in NC), and is characteristically a smooth/glabrous one almost throughout. The several paired, opposite leaves are rather thick and leathery, about 4.5" long, and normally lanceolate or narrowly triangular, clasping the stem at the base. They are generally smooth and about 1" wide, with small serrations. The fairly large inflorescence at the stem top contains numerous white flowers, each a bit over 1" long, and each is also notably inflated in the middle. The white flowers in P. pallidus are mostly under 1" long, are rather slender and are poorly inflated if at all; that species has clearly hairy stems and leaves. The numerous P. laevigatus is also mostly smooth, but its flowers are only about 7/8" long at best, as opposed to an average of 1.2" in P. digitalis, and P. laevigatus usually has light pink flowers. Considering its height, and large white flowers, a colony of these plants is the most spectacular in bloom of all of the Penstemon in NC. It is too bad we may never know if the species is truly native in the state or not!
Taxonomic CommentsNone

Other Common Name(s)Tall White Beardtongue
State Rank[SU]
Global RankG5
State Status[W4]
US Status
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