1900 | FLORA OF THE WHITE LAKE REGION 429 
Duck lake is similar to White lake but much smaller. Its 
southern shore is considerably higher than the northern. The 
water is clear and quite cool, being well supplied with springs 
and having only a small stream entering its head. There is a 
narrow belt of moving sand lying between it and Lake Michigan. 
To the south are high dunes, skirting the Michigan shore between 
itand Muskrat lake. The upper end is very reedy, and there 
is an abundance of aquatics in its shallow-parts. In White lake 
I had found the usual potamogetons to be P. pectinatus, P. perfo- 
liatus var. lanceolatus, P. lonchites, P. amplifolius, and P. heterophy!- 
lus. These were also common forms in Duck lake together 
with P. natans, P. zosteraefolius, and P. Robbinsit. The last had 
not reached the stage of mature fruit, which is in September and 
October, but was well provided with flowers and young fruit. 
This was interesting because it showed that the species may 
fruit under such conditions as potamogetons ordinarily do. It 
is usual to find the stems barren, and they are generally said to 
fruit, if they fruit at all, in shallow water or when ponds in which 
they grow partly dry up. This was the case in the only locality 
where I had previously found it fruiting freely, the Chesago 
lakes, Minnesota. It is very abundant ‘n some of the small lakes 
of northern Illinois, where the stems are mostly from one and a 
half to two or three feet long and very leafy. In Duck lake 
they were less leafy as a whole, the fruiting stems four to SIx 
feet loug, as this was about the depth of the water. They were 
rising and bringing the inflorescence to the surface of the water, 
or near to it, like P. pectinatus and the others with which it grew. 
All were flourishing equally well in the dark ooze which over- 
spread the bottom where they stood, and according to their atte 
Were equally well provided with fruit or the promise of it. ie 
was there any evidence of the shallowing of the water, excep 
the contrast between summer and the rainy season, vriccuened 
marked in a lake of this character fed by springs. 
The high dunes to the south of Duck lake had on their —. 
frequent patches of the yew, 7axus Canadensis. On the oe - 
slope of one whose base is washed by the waters of the lake 1 
