Vascular Plants of North Carolina
Account for Clustered Mountain-mint - Pycnanthemum muticum   (Michaux) Persoon
Members of Lamiaceae:
Members of Pycnanthemum with account distribution info or public map:
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Section 6 » Order Lamiales » Family Lamiaceae
Author(Michaux) Persoon
DistributionScattered statewide, being least widespread in the Piedmont. Possibly absent in some Piedmont and Coastal Plain counties (notably the Sandhills proper), but basically it occurs over the entire state.

This is an Eastern species ranging from ME and MI south to FL and eastern TX.
AbundanceInfrequent to fairly common in the Mountains and foothills; rare over most of the central and eastern Piedmont; uncommon to infrequent in the Coastal Plain, but rare in the far eastern counties.
HabitatThis is mainly a wetland species, growing in wet meadows, bogs, ditches, openings in bottomlands and swamps, and other damp ground. It does grow on some mountains, but there mainly where there is some seepage over rocks in forested sites.
PhenologyBlooms from June to August, and fruits from September to October.
IdentificationThis species is a typical mountain-mint, being about 3 feet tall, freely branched in the upper portions of the stem, and with numerous pairs of opposite leaves. The leaves tend to be ovate, nearly sessile, toothed along the margin, and about 2-3 inches long and half as wide. These species have rather flat-topped heads of about 1-2 inches wide at the ends of each branch, subtended by whitened bracts, with the flowers being very small and generally white with some purple spots on the lower lip. There are many such heads in bloom over the plant, often dozens of them. Separation of this species from others is technical and involves closely examining the calyx or the seeds. Use Weakley (2018) to key out the species. In the Coastal Plain, the only other numerous species (P. flexuosum and P. tenuifolium) have narrow leaves, generally less than 2/5-inch wide, and thus this wider-leaved species can be separated easily, as can the scattered heads at different levels on the plant, instead of a flat-topped appearance. However, to separate this from other species in the Piedmont and mountains, refer to the keys in Weakley (2018) and Wofford (1989). Note that this species grows mainly in wetlands, such as wet meadows, ditches, and bogs in these provinces, so that may be the first clue that this species is present and not one of the obligate upland species.
Taxonomic CommentsWeakley (2018) says there is an undescribed variety, named for now as var. 1; thus, there are two varieties in the state, with the other being the nominate var. muticum.

Other Common Name(s)Short-toothed Mountain-mint, Blunt Mountain-mint
State RankS4? [S4]
Global RankG5
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