Stems erect, grooved and angled, 1 to 4 feet high, slender and usually simple or slightly branched above, smooth. Leaves narrowly lanceolate, 3 to 8 inches long, one-fourth to 1 inch wide, entire, sessile or short petioled. Flowers violet or nearly white, in dense, short spikes or heads at the ends of the slender axillary peduncles which are shorter than or equal to the leaves in length; bractlets under the flowers linear-subulate and shorter than the flowers. Calyx deeply four to five-parted. Corolla two-lipped, about one-half of an inch long, the tube shorter than the lip, the upper lip erect, concave, entire; lower lip spreading and three-cleft, the base of the lower lip rough and palatelike. Fruit a capsule about one-half of an inch long, slightly compressed below.
Memoir 15 N. Y. State Museum
Water Willow - Dianthera americana
In wet places and shallow water along lakes, rivers and ponds, Quebec to Michigan, south to Georgia and Texas. Flowering from May to August.
Usually growing in dense colonies and from a distance easily mistaken for a coarse sort of grass. Very abundant along the Seneca river and along the shores of Oneida lake.