22, BIG SPRING PRAIRIE. 
Illinois, the sod, consisting of tangled sedges and 
grasses of the preceding year, and of the growing 
sedges and grasses, offered such a firm support that the 
marsh could be safely crossed by horses without the 
danger of miring, but at each step of the horses feet the 
ground would quiver for many rods in either direction. 
After the sedges and grasses were mown for hay by 
the settlers they would set fire to the dried sedges and 
grasses in the Autumn, in order that the areas might 
be more suitable for mowing the next year. This led 
to a curious but natural result. Whereas before these 
prairie fires cattle and horses could graze over this area 
without miring; after a repetition of these Autumn fires, 
the burned areas became so soft and treacherous, that 
cattle and horses frequently mired in them. 
Naturally the burning of the dead sedges and 
grasses prevented the formation of the dense carpet of 
tangled vegetable remains, and thus the upper crust 
being broken in places, the area became a true morass. 
This condition continued until ditches were dug and 
the land, for the time being, became fairly well drained. 
Besides the sedges and grasses the most common plants 
were 
Typha latifolia—(Cattails); 
Phragmites phragmites—(Reeds); 
Eupatorium perfoliatum—(Boneset); 
Aster (several species)—(Wild asters); 
Potentilla fruticosa—(Shrubby Cinquefoil); 
Betula pumila—(Low Birch); 
Rhus vernix—(Poison Sumac, or Poison Elder.); 
Helianthus (several species)—-(Wild Sunflowers); 
Riddellii > 
Solidago, and > Probably—(Goldenrods) 
Ohioensis j 
Some less common plants were 
Lacinaria spicata—(Blazing Star, or Gay Feather); 
Parnassia Caroliniana—(Grass of Parnassus); 
