67 
Vegetation of Delta Plains 
The following account of the delta plains is based upon collections and 
notes made chiefly during the month of August, 1930, at three places in 
Lake Mamawi district: the vicinity of the Government Dog Camp about 
4 miles south of the Quatre Fourches, the Cree (Mamawi) Creek district 
between the lake and Reed portage on the upper Embarras, and the chan- 
nels of Hay (Prairie) river on the west shore of the lake. To this material 
are added miscellaneous notes from the writer’s journeys through the Atha- 
baska and Peace deltas in the preceding four seasons, and the correlative 
data furnished by the aerial photographs. 
Figure 11 A is a generalized section illustrating this vegetation. 
AQUATIC ASSOCIATIONS 
The shallow lake contains large areas of pondweeds that are rooted in 
the mud bottom but whose upper stems and leaves float at the surface. 
The whole lake is so filled with them that it is nearly impossible to find a 
way across without getting into their tangled patches. The densest growth 
occurs near marshy shores and about the entrances to such channels as Cree 
creek and Hay river. 
Primary spp.: Potamogeton vaginalus 
P , Eichardsonii 
Secondary sp.: P. gramineus var. graminifolius 
There appears to be a succession of these species related to the depth 
of the water. P. vaginatm grows in the greatest depths, followed by 
P. Richardsonii. The secondary species is more common among the outer 
vegetation of the shore. 
SHORE ASSOCIATIONS 
On very gently sloping shores these associations merge in broad bands 
with those on either side of them, so that their exact margins cannot be 
designated. At the time of this survey it was possible to push a light canoe 
all the way through the shore vegetation and well into the first of the 
meadows, but such high water conditions were regarded as unusual by the 
local inhabitants. 
Primary spp.: Scirpus validus 
Potamogeton gramineus var. graminifolius 
Eleocharis palustris 
Secondary sp.: Glyceria grandis 
Eleocharis is not so generally distributed as Scirpus and Potamogeton, 
and Glyceria attains great abundance in a few places. As will be brought 
out in further records, Scirpus validus and Potamogeton gramineus var. 
graminifolius are the chief pioneers in colonizing this type of lake shore, 
and are general in such situations throughout the deltas. Where the section 
was made this association is about 20 yards wide. 
