1904 | WELD: BOTANICAL SURVEY OF HURON VALLEY 41 
the humus and contributing to it by their own decay, but their 
long petioles and large leaves break the force of the waves so 
that in the quiet water thus afforded a variety of less resistant . 
forms can grow, adding the products of their decomposition to 
that of the lilies and to the débris which they collect. 
The plants found growing here in the lily zone are: 
Nuphar advena, giving character te the zone and preferring shallower 
and more quiet water than the next; Nymphaea odorata, in two isolated 
patches only, as if recently introduced; Brasenia peltata, replacing the lilies 
in two places; Potamogeton natans, a few specimens; Ceratophyllum demer- 
sum, scattering, not in dense beds; Utricularia sp., close to shore not abund- 
ant; Chara sp., two flourishing clumps near shore, each about a foot square, 
apparently recently introduced; Naias flexilis. 
This zone then is made up almost wholly of Nuphar, which 1s 
replaced in spots by Nymphaea or Brasenia, while a very small 
number of other plants, represented by few individuals, grow on 
the soft, black, almost bare bottom. It would seem, therefore, 
that the yellow pond lily is an agent of prime importance in 
forming the soil in which various plants named in the following 
sections flourish. The relative importance of species in this and 
succeeding zones in the formation of peat should be inves- 
tigated. 
3. Carex and sphagnum zone. This is separated from the 
lily zone by a distinct though irregular line of demarcation. 
It presents a low, level appearance, being formed in great part 
of grasses and sedges uninterrupted by taller plants or shrubs 
(fig. 3). Its flora, however, is varied, consisting of about thirty 
species. Carex, with some six species, predominates; and, with 
several grasses, ferns, and other plants, forms a thick, tough, 
flexible mat resting on water or liquid mud beneath. This zone 
is less distinctly defined and the mat less compact, and hence 
less safe to walk upon, on the eastern than on the western side. 
Ordinarily, however, it will hold a man’s weight clear to the 
edge, even when the water is high in the spring, without break- 
ing. Some species of plants prefer the lakeward border, growing 
at or near the water’s edge; among these are the sensitive and 
flowering ferns, swamp milkweed, Dulichium, Eleocharis, and cer- 
tain other sedges, besides seedlings of Bidens and a mint, evi- 
