Lake Maxinkuckee, Physical and Biological Survey 217 



with the attached little blue-green or brown hemispheres of Rivu- 

 laria. Vorticella often finds a resting place on the leaves. Vari- 

 ous slender algae, particularly minute plants of GEdogonium, thickly 

 clothe the plants near shore, and in late autumn and winter, when 

 the diatoms are at their best, these plants are often covered so 

 thickly as to be almost unrecognizable, with fuzzy growths com- 

 posed of various species. Gathering the plants at such times is 

 one of the easiest ways of collecting diatomaceous material in 

 quantities. The plants, covered with a heavy growth in winter, 

 form a favorite haunt of various aquatic animals, such as may-fly 

 larvae and beach fleas. 



The plants were observed coming up thick and green at Knapp's 

 pier May 25, 1901. 



43. ROBBINS' PONDWEED 



POTAMOGETON ROBBINSII Oakes 



Potamogeton robbinsii is a fairly common weed in the lake, 

 growing either in deep or shallow water in rich muddy bottom. It 

 was dredged in water from 20 to 23 feet deep. Down towards 

 the Inlet it is found in water from 12 to 16 feet deep, and off 

 the icehouses it occurs plentifully in some place near shore in 

 about 3 feet of water. 



Although Robbins' pondweed never shows above the surface 

 (we have not even seen it in flower or fruit at the lake) it is by 

 no means inconspicuous for all that. It usually lies nearly pros- 

 trate on the bottom, and the 2-ranked widely-spread leaves, stand- 

 ing out almost perpendicularly on each side from the main stem, 

 give the effect of a scattered mass of graceful plumes lying in the 

 bottom. The whitish or yellowish cast of the plumes, due to a coat- 

 ing of lime on the old leaves, makes them all the more conspicuous 

 against the dark bottom through the clear water. This plant, 

 the graceful P. amplifolius, and the rank Megalodonta beckii and 

 Myriophyllum which stand up through the water like scared cats' 

 tails, add more than any of the other plants of the lake to the charm 

 of the subaquatic landscapes and make one long for a camera that 

 will take under-water pictures. 



P. robbinsii retains its form through the winter; the lower 

 leaves assume a brown and somewhat deadish look, but the tips are 

 firm and of a lively purplish green. 



This plant propagates largely by buds which could hardly be 

 called winter buds as they are often formed as early as the middle 

 of July and from then on through the winter. These buds are 



