292 NATURAL HISTORY OF THE FARM 
sedges, rather than of grasses. It is a place of abundant 
flowers the whole season through, from the cowslips and 
cresses of spring to the asters and gentians of autumn. 
It is a place where crawfish sink their wells, unmolested by 
the plow, piling little circular mounds of excavated earth 
about the entrance; a place where rabbits hide, and where 
song-birds build their nests; a place where the meadow 
mice and shrews spread a network of runways over the 
ground: in short, a place where rich soil and abundant light 
and moisture support a dense population, among which the 
struggle for existence is keen. 
If a fence-row extend down from the field into the swale, 
let us follow that, and see how the wild plants change with 
increasing soil moisture. The grasses of the fence-row begin 
to be crowded out by sedges as the water-level comes nearer 
the surface of the soil. Dry-ground asters and goldenrods 
and lobelias disappear, and wet ground species of the same 
groups appear instead. Bracken fern is replaced by marsh- 
fern and sensitive fern; hazel by willow. Under foot, the 
soil is growing softer, blacker and more spongy. 
If the swale has been cleared of woody plants, still alders 
and willows are prone to linger about the wetter places, and 
black-berried elder, osier-dogwood and meadowsweet about 
the edges. Cat-tails and bulrushes (fig. 16, p. 36) will fringe 
any open wet spot, and tussock-sedges and clumps of juncus 
will rise on mounds of gathered humus, like stumbling-blocks 
before our feet, where diffused springs abound. 
No two swales are alike in the character of their plant 
population. But all agree in their meadowlike appearance, 
in being made up of patches of rather uniform character, 
where uniform conditions prevail, and in having each of these 
areas dominated by one or two species of plants, with a 
number of lesser plants as “fillers” in its midst, and a greater 
variety of miscellaneous plants growing about its edges. 
