These underwater perennial plants sometimes occur as tangled masses in lakes, ponds, and ditches. Individual plants within each species vary in appearance depending on growing conditions. Some are bushy and robust, others have few leaves and weak stems. Both species have long, trailing stems with green, somewhat translucent leaves arranged in whorls of 3 around the stem.
This underwater rootless perennial plant has branched stems with stiff whorls of forked olive-green to almost black leaves. The leaves are sometimes coated with lime, giving them a crunchy feel. Coontail refers to the thick and bushy growth of leaves (similar in appearance to a raccoon's tail) that occurs at the stem tips. In nutrient rich water, coontail tends to form dense colonies either anchored in the mud or floating freely near the surface.
The exotic invader Hydrilla closely resembles common waterweed (Elodea), another noxious weed. All have bright green leaves arranged in whorls around the stem, although hydrilla leaves have small spines on the edges and at the tips. The most reliable way to identify hydrilla is to look for small potato-like tubers attached to the roots.
Purple loosestrife has vivid purple-pink flowers and blooms in summer and early fall. This erect, robust, square-stemmed, perennial crowds out native wetland species to form dense stands in shallow water and wet soil throughout Washington. It is important to recognize this invasive, rapidly-spreading European species because every effort needs to be taken to control its spread to new areas.
Spatterdock is a perennial plant with leaves that arise from a large spongy rhizome. The leaves have a slit that makes them roughly heart-shaped, 8 to 16 inches long by 10 inches wide, and can float on the surface or stand above the surface on thick round (in cross section) stalks. Flowers are spiracle with 6 to 9 green sepals and yellow petals. Flowers can float on the water or stand above it. Fruits are oval with a flat top and greenish or yellowish in color.
Although these common lake inhabitants look similar to many underwater plants, they are actually algae. Muskgrasses are green or gray-green colored algae that grow completely submersed in shallow (4 cm) to deep (20 m) water. Individuals can vary greatly in size, ranging from 5 cm to 1 m in length. The main "stem" of muskgrasses bear whorls of branchlets, clustered at regularly spaced joints. When growing in hard water, muskgrasses sometimes become coated with lime, giving them a rough gritty feel. These algae are identifiable by their strong skunk-like or garlic odor, especially evident when crushed.