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WSU/Pend Oreille Extension introduced the Sense of Place series in 1999, with a focus on local landscape and natural history of Pend Oreille County, Washington. A partnership with the Kalispel Tribe of Indians Natural Resources Department has allowed us to expand this program through EPA funding to include more classes, a newsletter and this website.

Edgers, Floaters and Sinkers

Plants Along the Pend Oreille River Corridor


by Meg Decker


It may seem that Eurasian watermilfoil is the only plant in the Pend Oreille River, but there are actually a variety of plants inhabiting the river corridor. They are important sources of food and shelter for all sorts of creatures. This article explores the three main categories of plants in and along our river and nearby waters. A) Edgers – those plants that inhabit the water’s edge (called emergent plants), B) Floaters – those who’s leaves and flowers float on the water’s surface, and C) Sinkers – those plants which are mostly submersed under the water’s surface.

The Edgers: These species of plants have their roots submerged below the water in the sediment. They have at least part of their stems, leaves and flowers above the surface. Some of these plants will be found along the water’s edge, while others can live in fairly deep water. These plants provide shelter and food for mammals, waterfowl and other birds, amphibians, fish and insects. They have also been important sources of food, medicinals, weaving material, and other uses for us humans.
In the Box Canyon Reservoir:
Sedges (Carex spp), cattails, horsetail and scouring rushes (Equisetum spp), rushes (Juncus spp), bulrushes, skunk cabbage, wapato (duck potato), water plantain, waterwort (mudwort), water smartweed, water pepper and watercress.

There are two plant species in this category that are invasive: Reed canarygrass and
purple loosestrife.


The Floaters: These aquatic plants live in three different categories.

1) Floating Leaves, Rooted Plants: These have their roots anchored in the sediment. The leaves float on the surface. Their stems are not strong enough to hold the leaves up when they are removed from the water. They provide food and cover for all sorts of animals as well as spawning habitat for fish and many uses for humans.
In the Box Canyon Reservoir: Rooted pondweeds (Potamegeton spp.) and waterlilies.
2) Floating Mats-Rooted: These plants have entangled leave and stems that make a mat on the surface of the water. They are usually fairly close to the shoreline. These are mostly found on the coast and in the lower regions of the Columbia River.
3) Free Floaters: This group tends to include mostly small plants with dangling roots. They may inhabit the water’s surface, be within the water column, or hang out down near the bottom. They will often form mats. These plants provide a high protein food for fish and waterfowl. They also are good habitat for aquatic invertebrates.
In the Box Canyon Reservoir: Water lentil/duckweed (Lemna spp.) and great duckweed.

The Sinkers: Submersed plants that have their roots in the sediment. The entire plant is mostly underwater, but the flowers are often on the surface. They grow anywhere from the water’s edge to depths more than 30 ft. They range from tiny delicate plants to the robust milfoils.
In Box Canyon Reservoir: Coontail, waterweed, water-starwort, pondweeds, water star-grass (a rare species), water buttercup, bladderwort, and the milfoils.

The bad guys in this category are Eurasian watermilfoil, Brazilian waterweed and curly pondweed.

Along with all of these plants, our waters are also inhabited by different species of algae, mosses, and bluegreen algae. We also have freshwater sponges and Bryozoans, which are simple, colonial organisms sometimes mistaken for plants.

All of the plants listed above were observed in the Box Canyon Project Area in a 1996-1998 survey by the PUD for their relicensing of Box Canyon Dam. Seattle City Light will be doing a similar survey next year. Another important source of information is “An Aquatic Plant Identification Manual for Washington’s Freshwater Plants” published by the Washington State Dept. of Ecology. This manual is available online at http://www.ecy.wa.gov/programs/wq/links/plants.html

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