TORREYA 



kotamcal 



Vol. 24 No. 4 



July-August, 1924 



SWAMP AND BOG PLANTS: IRIS VERSICOLOR L. 

 Frank C. Gates* and Elsie E. Erickson 



The differentiation between bogs and swamps has been of 

 considerable interest in the past and it can not be considered as 

 solved at the present time. Possibly there never will be any 

 conclusion beyond stating that swamps and bogs form ends of a 

 linear series, intergrading freely. In his studies in bogs and 

 swamps, the senior author has endeavored to find different plants 

 which grow imder both conditions to see whether any structural 

 differences are discernible. One such plant is Iris versicolor L. 

 Iris versicolor is a rather common swamp plant in Northern 

 Michigan, but it also grows in bogs, although sparingly. It is 

 best developed in swampy places just back of the shores of lakes 

 where protection is afforded from wind, waves, ice and sand. 

 The plant is a perennial herb, with a thickened, somewhat 

 branched subterranean stem growing 2.5 to 10 to 25 cm. or more 

 below the surface of the soil and bearing a few leaves and a 

 flowering stalk at the tips. The roots extend outwards and 

 downwards from the rootstocks. The leaves are flat, sword- 

 shaped, light-green, parallel-veined and smooth. They are held 

 in a vertical position by their sheathing bases. The flowers of 

 Iris are too well known to need description here. The fruit is 

 a long, more or less triangular, three lobed, stout-beaked, many- 

 seeded capsule. 



The following study was made under the senior author's 

 direction at the University of Michigan Biological Station on 

 Douglas Lake, Cheboygan County, Michigan, during the sum- 

 mers of 1922 and 1923 by Miss Elsie E. Erickson. The aim was 

 to discover, if possible, some way of telling whether a given 

 plant of Iris had grown in a bog or in a swamp. In each of 

 several different areas in the region, investigation was made of 

 CnI the growth structures of the plant, after which typical individuals 

 ■«— were brought into the laborator^^ sectioned and studied. 



«^0 * A contribution from the Biological Station of the University of Michigan 

 C^ and from the Botanical Laboratory of Kansas State Agricultural College 



Ca No. 195. 



:^ 55 



