70 
above. On shores exposed to wave action, as at the Government Dog 
Camp, the marsh has nearly disappeared, and the alluvial soil is cut back 
to such an extent that the Calamagrostis meadow grows on a low bank at 
the water's edge. This was also noted on the east shore of lake Claire, at the 
western end of Hay river. The waves not only cut back the shores but 
also they pile up low ridges of debris which lead to a more mesophytic vege- 
tation in the form of willows. A thin line of willows is clearly seen along 
the east side of lake Mamawi (Figure 10). Plate X B is a photograph 
of storm waves actually eroding the shore at the Dog Camp. 
SHRUB ASSOCIATIONS 
Low ridges on the margins of stream channels, old mud bar forma- 
tions around the bases of granite hills, and certain shores subject to wave 
erosion have willow groves covering them and pushing out into the drier 
parts of the Calamagrostis meadows. The pioneer species is usually Salix 
; planifolia . A considerable number of other species occupy the loose growth 
of willows at the margins of the groves. 
Primary spp.: Salix planifolia 
Calamagrostis canadensis 
Secondary spp.: Poa pratensis 
Pha laris arun din acca 
Salix peliolaris 
S. lasiandra 
S. Bebbiana 
Vrtica gracilis 
Polygonum natans forma Hartwrightii 
Rumex mexicanus 
Ranunculus pennsylvanicus 
Anemone canadensis 
Potentilla Anserine 
Geuni striatum 
Sium suave 
Cicuta occidentalis 
Mentha canadensis var. glabrata 
S tacky 8 scopulorum 
Pkysostegia parviflora 
Achillea sibirica 
Erigpron philadelphicus 
Solidago canadensis 
Aster junceus 
Only the primary species have any importance as ground cover, since 
the others are much scattered in the partial shade of the willow chimps. 
Following this open association comes a dense growth of willows whose 
slender trunks are so interlaced as to be nearly impenetrable, and which 
cause a deep shade. The ground vegetation under them is sparse and com- 
posed of plants that are prominent elements in the shrub and ground covers 
of the poplar and spruce forests. 
Primary sp.: Salix Bebbiana 
Secondary spp.: Equine turn pratense 
Corallonhiza trifida 
Ribes oxyacanthoides (seedling) 
Rubus idaeus var. canadensis (seedling) 
Vicia arnericana 
Cornus stolonifera 
Viburnum pauciflorum (seedling) 
Aster Lindleyanus 
