Pycnanthemum tenuifolium, the narrowleaf mountainmint, slender mountainmint, common horsemint or Virginia thyme, is a perennial herbaceous plant in the mint family, Lamiaceae. It is native to central and eastern North America. Description Pycnanthemum tenuifolium is an herbaceous plant with wiry, green, branching stems from tall. As with other mints, the stems are square in cross section. Leaves are narrow, opposite, and simple, measuring up to long and less than wide. The flowers are white, borne in dense, half-round heads in summer, June through September. Unlike most plants in the genus, the foliage has a very faint mint fragrance. Etymology Pycnanthemum is based on the Greek words pyknós (dense) and ανθέμιον (flower). Tenuifolium is from the Latin words tenuis (thin) and folium (leaf). Distribution and habitat P. tenuifolium is native to central and eastern North America, from Texas in the west to Maine in the east, Canada in the North, and Florida in the south. Native habitats include dry, open, rocky woods, dry prairies and fields, roadsides, pine barrens, streams, and open wet thickets. Ecology The plant attracts native bees, bumblebees, honey bees, and butterflies. References External links USDA Plants Profile for Pycnanthemum tenuifolium (narrowleaf mountainmint) USDA NRCS Plant Guide: Pycnanthemum tenuifolium tenuifolium Flora of Eastern Canada Flora of the Northeastern United States Flora of the North-Central United States Flora of the United States Flora of the Southeastern United States Flora of the Appalachian Mountains Flora of the Great Lakes region (North America) Least concern flora of the United States Plants described in 1809