386 IOWA ACADEMY OF SCIENCE Vol. XXV, 1918 



habitat makes it a good invader. Melilotus alba has a tough 

 biennial root and fairly wide range of habitat, having a ten- 

 den<rv^ to endure arid conditions. It is rapidly invading a dry 

 giavelly knoU of one of the prairie hills along Squaw creek 

 which is pre\'iously described as a stronghold of the intensive 

 rooted Andropogons, Asters and Solklagos. 



Invasion of the Alluvial Basix Meadow. 



This blue grass — sweet clover type of invasion has taken place 

 in the last five years in the alluvial basin region below Heuchera 

 hill (See Lists) and in the vicinity there has been a rapid dis- 

 appearance of the majority of the original plants, yet a few rep- 

 rosentaitives of the original formation remain, among which are 



I'ig. Hiii. — i-"orest bordering Squaw creek achaming toward the prairie. 



Panicum virgatum, Senecio auremn, Fragaria virginiana, Sium 

 cicutaefolium, Cicuta maculata, Veronica virginica, Lohelia 

 spicata. No decrease is noted in the number of plants of Bap- 

 tisia leucantha. Tliis plant has a long, tough, thick, deep 

 branched root which is a good reinforcing character. It stands 

 above the surrounding plants and thus has light advantages. 



The pond adjacent to the wet meadow area lies also in the 

 pasture but has apparently not been affected. No species have 

 disappeared. 



The swamp, though cut late in the year for hay, shows no 

 chaaige in its constituent species except that a willow thicket 

 has grown up along a ditch beside a fence where the grass is not 

 cut. Willows constantly appear in this wet area but are mowed 

 off yearl3^ 



