Pycnanthemum tenuifolium is a perennial herb to 80 cm, colonial from rhizomes, hardly aromatic, very leafy, many short axillary branches.
Leaves opposite, linear, to 5 cm long, 0.4 cm wide.
Flowers white with purple spots, bilaterally symmetrical, tubular, to 0.8 cm long, 2-lipped, lower lip 3-lobed, calyx lobes linear, flowers in numerous small heads, basal bracts of head narrow often longer than heads, inner bracts numerous; blooming June-Sept.
Fruit dry nutlets; fruiting Sept. – Oct.
Wetland status: FACW.
Frequency in NYC: Very infrequent.
Habitat: Moist to dry soil, fields, bogs.