ROOTED AQUATIC PLANTS IX LIMNOLOGY 



113 



<;HALLQW WAlrRCQMMUNIILS 



— Boulder Colonists 



Lobelia 



35-80 



fluiTonj 



10-90 



PoTamoqfTon * ' UunqpliuJlufn 



10-40 \ '3S-9b 



LasTalm alba \ LasTalia minor"* *r. naians 



lO-JJ" \ \ 10-80 \ / 60-90 



ii >« 



Numphapa lutea 

 ^ 24-55 I 



Stirpus 

 PhrajmiU: 



lupha latifolia 

 Rgpij siltinj MoJgraTf 5ilTin^ 



(P« 





picture of aquatic plant succession for tliat 



Fig. 3. Diagram of plant succession among com- 

 munities of plants in areas of soil erosion or where 

 soils have accumulated and formed shallow water. 

 The figures indicate the percentage of organic con- 

 tent in the soils. 



In the United States a number of papers 

 have been published that deal with general 

 descriptions of aquatic plant distribution. 

 Few. however, deal with the succession of 

 this vegetation. Gates (1926) published 

 two diagrams for the Douglas Lake region 

 of northern ^Michigan, but these need ex- 

 pansion before they can give a complete 



region. 



Fassett (1930) published some observa- 

 ions on the lakes of northeastern Wisconsin 

 ill which he not(>(l that different types of 

 acpiatic plants were preponderant in dif- 

 ferent lakes and that the lakes inhabited by 

 each type had in common certain features 

 of transparency, hydrogen-ion concentra- 

 tion, etc. No decision was made concerning 

 which, if any, of these factors functioned in 

 determining the growth of each plant. 



The plant types listed by Fassett are as 

 follows: (1) plants with long flexuous 

 stems and compound or flexuous leaves, the 

 whole supported by the water; (2) plants 

 with stiff leaves in a close rosette or on 

 short, rigid unbranched stems; (3) plants 

 with the vegetative stem horizontal and 

 the leaves mostly or entirely floating on the 

 surface of the water; (4) and plants with 

 their bases in the water and photosynthetic 

 parts mostly or entirely emersed. Steenis 

 (1932) has added a fifth "growth form," 

 which includes those plants that float on 

 the surface such as Lemna, and SjnrodeJa. 









-'•- J 



^^^ t X ;^ •" V •» - -^ «^ . 





Fig. 4. Silver Lake, Yilas County, Wis. A clear, medium hard-water lake of the intermittent drainage 

 type, in a youthful stage of development. The flora is rich in submerged, floating, and emersed types. 



