''Penstemon alluviorum'', known by the common name lowland beardtongue, is a species of

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

in the veronica family. It is native to the Eastern United States where it is found in

alluvial Alluvium (from Latin ''alluvius'', from ''alluere'' 'to wash against') is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. Alluv ...

lowlands, particularly of the

Mississippi Mississippi () is a state in the Southeastern region of the United States, bordered to the north by Tennessee; to the east by Alabama; to the south by the Gulf of Mexico; to the southwest by Louisiana; and to the northwest by Arkansas. Miss ...

and

Ohio River The Ohio River is a long river in the United States. It is located at the boundary of the Midwestern and Southern United States, flowing southwesterly from western Pennsylvania to its mouth on the Mississippi River at the southern tip of Illino ...

s. ''Penstemon alluvoirum'' is a poorly understood taxon. The differences between this and two related species, '' Penstemon digitalis'' and ''

Penstemon laevigatus ''Penstemon laevigatus'', the eastern smooth beardtongue, is a plant in the plantain family, Plantaginaceae. The flowers are borne in summer. Its native range includes much of the Eastern United States, from Maine to Michigan and Georgia to Miss ...

'', are not well resolved. It is identified within the complex by having corollas that are 15–23 mm long, sepals that are 3–6 mm long, and leaves that are 25–40 mm wide. It produces white (rarely lavender) flowers in May.Flora of the Southern and Mid-Atlantic States
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References

alluviorum Flora of the Eastern United States {{Plantaginaceae-stub