31 
validus, or cow lilies Nymphozanthus vanegatus, or both, with occasion- 
ally other emergent sedges and 'grasses. At the actual shore-line are sucl) 
characteristic species as cat-tail Typha latijolia, or some species of bur- 
reed Sparganium, or sedge Car ex. There is usually a slough or wet mea- 
dow back from the shore, dominated by sedges and grasses, and margined 
by willows. The main deviations from this trend occur on very steep, 
rocky, or sandy shores and on mossy borders of muskeg ponds, as the fol- 
lowing discussions will show. 
More or less detailed studies of upland lake shores have been made 
at Moose lake, Pine lake, a small lake near upper Salt river north of Pine 
lake, at a small lake near the base of Caribou mountains about 20 miles 
north of Indian graveyard, Peace river, and at some small lakes southeast 
of Pine lake. The main results of these studies have been checked with 
a large number of minor observations throughout the region, so that the 
writer is confident that they are fairly typical. 
AQUATIC ASSOCIATIONS 
The deepest parts of the sink-hole lakes seem to be quite barren of 
vegetation. A great many soundings were made in Pine and Lane lakes 
in an effort to determine the contours of the bottoms, and the alga, Chara, 
was brought up only from bottoms about 25 feet deep or less. Shallower 
lakes have a rich growth of this plant which rises in billowy masses, some- 
times to the surface. The water birds at Moose lake in mid- July were 
using these off-shore masses as temporary roosts. In a few localities the 
accumulations appear to be forming the basis for the growth of other 
aquatic plants. In most of the lakes there is an abundant plankton con- 
sisting of green and blue-green algae as well as many minute animal 
organisms. 
A few sink-hole lakes are of such inverted-conical form that they 
have no marginal aquatic vegetation at all. There are several of these near 
the trail between Moose and Pine lakes, and a few notable examples along 
the wagon road east of Pine lake. Scarcely any peaty materials have 
accumulated on their steep bottoms, and from the edge one may look down 
many feet through the clear water. Pioneer plants on less steep shores are 
usually species of Potamogeton. These are rooted in the bottom, and by 
their semi-floating, supple nature, are admirably adapted to withstand 
wave action. Although many observations will be required to prove the 
point, peaty bottoms appear to favour the broad-leaved P. praelongus, 
whereas sandy, gravelly, or muddy bottoms grow the narrow-leaved P, 
vaginatus or P. pectinatus. Both P. praelongus and P. pectinatus were 
found in abundance in typical situations at Moose lake. P. Richardsonii 
is sometimes found in place of P. praelongus . In the second and third 
weeks in August, 1929, the latter species in Moose lake had its leaves 
broken and encrusted with lime, and was losing its ripe fruits. The floating 
bladderwort Utricularia vulgaris , and water-milfoil Myriophyllum exal- 
bescens, sometimes accompany the pond weeds and Chara in peaty ponds, 
and in muskeg ponds they grow with the peat mosses that extend out 
91963—3J 
