Vascular Plants of North Carolina
Account for Slender Mountain-mint - Pycnanthemum tenuifolium   Schrader
Members of Lamiaceae:
Members of Pycnanthemum with account distribution info or public map:
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Section 6 » Order Lamiales » Family Lamiaceae
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DistributionThroughout the Mountains and Piedmont, and also essentially throughout the northern half of the Coastal Plain. It appears to be absent from the far eastern counties, and scarce in the southern Coastal Plain.

This is a widespread Eastern species, being found in most counties from ME and IA south to western FL and eastern TX.
AbundanceCommon in the Mountains, common to very common in the Piedmont, and fairly common to locally common in much of the northern and central Coastal Plain. Scarce to absent in the far northeastern and parts of the southern Coastal Plain. This is the most abundant Pycnanthemum species in NC.
HabitatThis is a species of slightly damp ground, but hardly an obligate wetland species. It grows best in wet meadows, moist spots in powerline clearings, edges of mesic to moist woods, bogs, and other mostly sunny spots with some moisture, but it does not normally occur in strongly acidic soil such as in savannas or pocosins.
PhenologyBlooms from June to August, and fruits from September to October.
IdentificationThis is the easiest of the numerous mountain-mint species in NC to identify, owing to its very slender leaves. It grows only to about 2 feet tall, shorter than the others in the genus. It is branched in the upper portions, and has an abundance of pairs of opposite leaves each being linear, about 1.5 inches long but barely 1/10-inch wide, with entire margins. At the tops of the uppermost branches are small and dense heads of very small white to rarely pink flowers, each head only about 1/4-inch across, but large numbers grow together in a flat-topped inflorescence 3-5 inches across. Thankfully, the species usually grows in colonies, to produce an extensive white patch in its habitat. P. virginianum is quite a bit similar but has wider leaves and a pubescent stem, at least on the angles; P. tenuifolium has glabrous stems. It is a frequently encountered species over much of the state, especially in powerline clearings.
Taxonomic CommentsSome older references had this species included within P. flexuosum, which makes little sense.

Other Common Name(s)Narrowleaf Mountain-mint
State RankS5
Global RankG5
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B.A. SorriePiedmont, roadside of NC 24/27 W of Carthage. 9 July 2018. MoorePhoto_natural
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