A perennial aquatic herb, rising from a thick, horizontal rootstock, with thick, glossy, dark-green, ovate to lanceolate leaves, cordate-sagittate, truncate or narrowed at the base, 2 to 10 inches long, 1 to 6 inches wide, the apex and basal lobes obtuse. Flowering stems erect, 1 to 4 feet tall, glandular-pubescent above, one-leaved, with several sheathing, bractlike leaves at the base. Flowers blue, ephemeral, numerous, in a dense head or spike (spadix) subtended by a thin bractlike spathe. Each flower is tubular, about one-fourth of an inch long, curved, two-lipped, the upper lip composed of three ovate lobes, of which the middle one is the longest, and with two yellow spots at the base within, the lower lip of three linear-oblong spreading lobes. Stamens six, the filaments, anthers and style bright blue. After flowering, the lobes and upper part of the perianth tube wither above, while the persistent base hardens around the fruit.
Frequent along the borders of ponds and streams and shallow margins of lakes, where it flowers from June to September, usually at its best in August. One of the most attractive of our native aquatic plants.
The Pickerel Weed belongs to the Pontederiaceae, represented in our flora by but one other genus, the Mud Plantains (Heteranthera), with two species of small, inconspicuous herbs of shallow water or wet muddy shores.
Memoir 15 N. Y. State Museum
Pickerel Weed - Pontederia ccrdata