Forest Preserve District of Cook County, Illinois
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Freshwater Shore Lines
Nature Bulletin No. 531-A   May 25, 1974
Forest Preserve District of Cook County
George W. Dunne, President
Roland F. Eisenbeis, Supt. of Conservation

FRESHWATER SHORE LINES
Ashore is more than a line on a map where land meets water. Whether it is the edge of a creek, river, lake or pond, a shore is a long narrow world of its own, separate and distinct from the broad land mass and the sheet of water next to it. Along this line many living things, both plant and animal, crowd in and lead a double life -- part time on land and part time in water. They form a community which is always active.

A conspicuous feature of most shores is a band of luxuriant upstanding vegetation. As the water level rises during rainy weather or falls during times of drought, this strip is alternately flooded or left stranded. There is always a crop of marginal plants except on streams whose banks are regularly scoured by freshets: or on lakes where high waves pound over a sandy beach; or on artificial reservoirs where the water levels fluctuate greatly because they are used for flood control, water power or water supply.

Commonly, the different kinds of shore plants are arranged in zones. Some of the bulrushes, for instance, grow upward from water so deep that their roots are always submerged. The cattail, arrowhead and others are in a higher zone -- sometimes in shallow water, sometimes on wet mud. Still others, including such trees and shrubs as willow, silver maple and buttonbush, grow above them where the soil is kept moist by water drawn from below. The widths of these zones and the kinds of plants in them depend on the slope of the shore, its type of soil, and the changes in water level during the course of a season.

The Arrowhead, with broad glossy spear-shaped leaves, thrives on muddy shores of both streams and lakes. The same plant growing in a foot of water may have leaves as slender as a pencil. Its flowers, each with three filmy white petals, appear in groups of three throughout the summer. At the ends of long underground runners it bears starchy tubers the size of a hen's egg. These are eaten by waterfowl and muskrats -- hence the name Duck Potato. On their journey to the Pacific Coast in the early 1800's, the Lewis and Clark Expedition bartered for quantities of these tubers from the Indians who called them Wapato.

The Great American Bulrush sends up tall slender whip-like stems from a mat of interlocking rootstocks below the low-water mark. They help anchor loose soil and build new land. Their fruiting stems bear loose clusters of seeds which, with the starchy roots and the bases of stems, furnish an abundance of food for muskrats, wild ducks and shore birds.

Among the more common large shore plants of this region are the Sweet Flag which, from its thick aromatic underground stem, yields the drug calamus; the Pickerel Weed with its leathery green leaves and tall spike of blue flowers; the Water Smartweed with its heads of "shocking pink" blooms; and a host of different kinds of sedges and grasses.

The animal life of a shore is as distinctive as its plants. In or near this vegetation are to be found the nests of the marsh wren, the red-winged blackbird, coots, rails and little green herons. Water-dwelling toads and salamanders lay their eggs in the water. Mink and raccoons prowl the water's edge for crayfish, frogs, snails and snakes.

Small boys come prowling after them.


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