3i4 



NATURAL HISTORY BULLETIN. 



tured the upland prairie sedges are quickly destroyed, but 

 those found in the woods where the shaded ground retains 

 moisture better, survive much longer. 



When we consider the great number of species in the sedge 

 family, and their wide geographical distribution, it is remark- 

 able that an introduced foreign species is so rarely met, there 

 being but a very few in the United States, and so far as 

 known, not one within the limits of Iowa. Compared with 

 the Graminece in this respect the difference is very striking. 

 The troublesome introduced grasses of our state are, with 

 one or two exceptions, annuals, and all well fitted by nature 

 for the rapid dissemination of their seed into new localities 

 by man's agency as he carries on his agricultural operations, 

 even though he may do his best to prevent it. The carices 

 which comprise much the greater part of the sedge flora of 

 the land suitable for cultivation being perennials are ill fitted 

 to survive where the soil must be frequently turned by the 

 plow, but in Cyperus esculent us L. we have at least one excep- 

 tion, which on account of its numerous, small tubers is able 

 to live in low cultivated land, and is troublesome in some 

 localities. 



In the distribution of our native plants into new localities 

 by natural agencies the wind is a very important factor, but 

 with the exception of a few species the distribution of the 

 sedges by this means is comparatively slow. The fruit of 

 such plants, however, as the species of Eriphorum, is quite 

 well fitted for rapid distribution by high winds. The seeds 

 of most of our Composite?, and many other plants which mature 

 late in autumn, are often carried great distances over the crusted 

 snow by the strong winter winds, but the fruit of the sedges, 

 with very few exceptions, is not retained on the plants long 

 enough to avail of this latter means of transportation. To 

 the action of waves on our ponds and lakes, and to the cur- 

 rents of streams, especially during high water, we must 

 attribute much credit for the distribution of the seeds of 

 sedges. This is especially true of those carices having an 

 inflated perigynium which are thus enabled to float very 



