The leaves of all Pycnanthemum species have a strong mint fragrance that can even be smelled in museum specimens decades old. Many members of the genus have been used medicinally to treat digestive and other disorders.
There are only 4 verified occurrences and 5 historical occurrences known in New York.
More work is needed to determine the short-term population trends for this species, as most verified occurrences are small and have only been visited once.
There are equally small numbers of both historical and verified populations for this species in New York. It has likely always been rare in the state, though some populations have been overlooked.
Ditching and spread of the invasive grass species Phragmites australis are threats at one of the fen sites. Succession and ATV use are potential threats at both the fen and dune sites.
Mowing or clearing, if done after the growing season, may benefit this species at sites which are succeeding to woody vegetation.
In New York, Whorled Mountain-mint has been found in fens, inter-dunal swales, and other open, calcareous wetlands, usually on wet sandy substrates(New York Natural Heritage Program 2008). Dry to moist thickets, clearings, swales or wet peat (Fernald 1970). Upland woods and thickets (Gleason & Cronquist 1991). Abandoned fields, swampy meadows, marshes, and woods (Rhoads and Block 2000).
Pycnanthemum verticillatum var. verticillatum is known from Richmond, Suffolk, Ulster, and Delaware Counties in southern New York, and there is a single known population in St. Lawrence County.
Pycnanthemum verticillatum var. verticillatum is found along the U.S. Atlantic Coast from Maine to Georgia, and inland as far west as Ontario, Michigan, Kentucky, Tennessee, Missouri, and Arkansas.
Pycnanthemum verticillatum var. verticillatum is a rhizomatous herb with branching, square stems up to 1.5 m tall the stems minutely pubescent throughout. Like other Mountain-mints it is strongly aromatic, such that a strong spearmint odor from the leaves may be the explorer's first clue to its presence. The leaves are narrowly lance-shaped, 3-5 cm long and only 8-12 mm wide, with an acute tip, and hairy only along the veins of the lower surface. The flowers are crowded into numerous heads 8 to 15 mm thick, and subtended by leaf-like bracts They are white, and two-lobed, the lower lobe purple-spotted. The teeth of the sepals (calyx) are narrowly triangular, acuminate, and .5 to 1 mm long. Variety verticillatum is the only native variety of Whorled Mountain-mint found in New York. Pycnanthemum verticllatum var. pilosum, a non-native variety, has been reported from Wayne County. Its leaves are pubescent throughout their lower surfaces.
Specimens with stems, leaves, and either flowers or mature fruit are needed to identify this species.
Pycnanthemum torrei has leaves and bracts which are glabrous on the upper surface, and softer and less veiny than those of P. verticillatum . P. torrei also has longer (1 to 1.5 mm) and sharper calyx teeth (Gleason and Cronquist 1991). Pycnanthemum virginianum stems are pubescent only on the angles (Rhoads and Block 2000).
Whorled Mountain-mint flowers from July through August, and the fruits may persist into mid-October.
The time of year you would expect to find Whorled Mountain Mint flowering and fruiting in New York.
Whorled Mountain Mint
Pycnanthemum verticillatum var. verticillatum None
The other variety of Pycnanthemum verticillatum, var. pilosum, has been collected from just one location in the state, and is not considered native to New York.
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Holmgren, Noel. 1998. The Illustrated Companion to Gleason and Cronquist's Manual. Illustrations of the Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York.
Mitchell, Richard S. and Gordon C. Tucker. 1997. Revised Checklist of New York State Plants. Contributions to a Flora of New York State. Checklist IV. Bulletin No. 490. New York State Museum. Albany, NY. 400 pp.
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Newcomb, Lawrence. 1977. Newcomb's Wildflower Guide: An Ingenious New Key System for Quick, Positive Field Identification of the Wildflowers, Flowering Shrubs, and Vines of Northeastern and North-Central North America. Little, Brown and Company. Boston.
Reschke, Carol. 1990. Ecological communities of New York State. New York Natural Heritage Program, New York State Department of Environmental Conservation. Latham, NY. 96 pp. plus xi.
Rhoads, A.F. and T.A. Block. 2000. The Plants of Pennsylvania: An Illustrated Manual. University of Pennsylvania Press: Philadelphia, Pennsylvania. 1061 pp.
Weldy, T. and D. Werier. 2010. New York flora atlas. [S.M. Landry, K.N. Campbell, and L.D. Mabe (original application development), Florida Center for Community Design and Research http://www.fccdr.usf.edu/. University of South Florida http://www.usf.edu/]. New York Flora Association http://newyork.plantatlas.usf.edu/, Albany, New York
Information for this guide was last updated on: May 22, 2008
Please cite this page as:
New York Natural Heritage Program. 2020. Online Conservation Guide for Pycnanthemum verticillatum var. verticillatum. Available from: https://guides.nynhp.org/whorled-mountain-mint/. Accessed July 9, 2020.