Marsh or immersed aquatic herbs with slender, jointed, leafy stems; leaves flat or filiform, sheathing at the base; flowers perfect or unisexual with a perianth of four or six distinct valvate or tubular segments; fruit an indehiscent berry.
I. Potamogeton. (Touril.) L.
1. P. Richardsonii. (Benn.) Rydb. Richardson's Pond-weed. 2. P. filiformis. Pers. Filiform Pondweed.
Herbs with creeping rhizomes and hollow stems, mostly perennial; leaves alternate, sheathing, channelled or terete; flowers perfect, small, spicate, or racemose with six-lobed perianth; fruit capsular or follicular.
I. Triglochin. L.
1. T. palustris. L. Marsh Arrow Grass.