Water HorehoundLycopus americanus
This native perennial plant is about 1-3' tall, sometimes branching sparingly near the base. The green or reddish central stem is four-angled and ridged; it may be hairless or slightly pubescent. The opposite leaves are sessile or have short petioles, and somewhat widely spaced along the stem. They are up to 3" long and ¾" across, and usually lanceolate or ovate-lanceolate in overall shape. The lower leaves are lobed or pinnatifid toward the base, while the upper leaves are coarsely dentate all along their margins.
Axillary whorls of white flowers occur where the upper pairs of leaves join the stem. Each flower is about 1/6" long, and has a tubular corolla with 4 spreading lobes. There are two stamens with brown anthers that are exerted outside the corolla. The blooming period is from mid-summer to early fall, and lasts about 1-2 months.