Lake Maxinkuckee, Physical and Biological Survey 135 



eral locality where other species grow will be taken up in discussing 

 the various species. 



While considering the question of permanence and position of 

 plant-patches in the lake it may not be out of place to refer to un- 

 attached plants, including the floating duckweeds, and of course, 

 the alga-masses, but more especially those anomalous forms which 

 have no roots developed, such as Ceratophyllum and Utricularia. 

 There is nothing among land plants which is analogous to them. 

 The tumble-weeds suggest them somewhat, but the disassociation 

 of the tumble-weed from its roots is for the sake of great motility 

 and distribution of seeds, while the Ceratophyllums and Utricu- 

 larias are loggy, hardly affected at all by currents of air and little 

 by currents of water. They really appear to be forms of im- 

 mensely overgrown propagating buds, and, although they produce 

 seeds, are themselves largely propagated by vegetative reproduc- 

 tion. 



In entering upon the discussion of the several species of plants 

 which inhabit the lakes, it has been thought best to take them in 

 the order in which they occur, first disposing of the floating forms, 

 and then beginning with those inhabiting the deeper waters, and 

 proceeding from thence toward the shallow water. The usual 

 method of taking plants m the order of their supposed relationships 

 has been avoided, chiefly because they occur in that order in the 

 general list accompanying this report, and partly because the ques- 

 tion of genetic relationship is not here the one primarily under con- 

 sideration. It was thought best to begin with the center and pro- 

 ceed centrifugally, because there is no doubt of where to begin 

 here, while beginning at the shore would leave no definite starting 

 point. Considering species in the order suggested, moreover, will 

 present them in the societies in which they occur as nearly as that 

 can be done. 



The floating aquatics, including the rootless phanerogams, 

 Ceratophyllum, the various species of Utricularia, the minute float- 

 ing duckweeds, and the unattached algal masses, such as Spirogyra, 

 Mougeotia and the like, form a class by themselves. Ecologically, 

 they belong in the group with the plankton. Theoretically speak- 

 ing, these plants have no local habitation but drift hither and yon 

 as currents and winds drive them. As a matter of fact, they are 

 not so continually in motion as one might imagine, the algal masses 

 often becoming tangled in the tops of the rooted plants, the loggy 

 submerged Ceratophyllum and Utricularias responding very little 

 to winds, and the duckweeds occupying nearly the same position 

 year by year in the sheltered nooks. The duckweeds are always 



