75 
tion consists mainly of species of horsetail Equisetum. Where the current 
is sufficiently gentle to permit it, E. limosum forms dense, nearly pure 
growths in the quiet water along shore and in the mud of the lower banks. 
The Equisetum association attains its greatest purity in the upper parts 
of the deltas, and when seen near the actual mouths of the rivers is asso- 
ciated with a number of slough margin species drawn from surrounding 
habitats. The secondary species listed below were collected at the place 
where Embarras channel makes its last branching before entering lake 
Athabaska, All stages in the sorting out of this complex appear between 
this point and the upper parts of the Embarras. The same stages may be 
seen along the Quatre Fourches and along Cree creek, although the latter 
no longer has a current. 
Primary sp.; Equisetum limosum 
Secondary spp.: Typha lo It folia 
Sagitlaria cuneata 
Alopecurus aequalis 
Glycerin borealis 
G. grandis 
Pkalaris arundinacea 
Beckmannia Syzigachne 
Poa palustris 
Phragmites communis var. Berlandieri 
Pucci, ne Ilia Nuttalliana 
Carex trichocarpa var. aristata 
Eleocharis acicularia 
E. paluslris 
Scirpus validus 
J uncus nodosus 
Rumex maritimus var. jueginus 
R. mexicunus 
Ranunculus pennsylvanicus 
R. sceleratus 
PotentUla norvegica var. hirsuta 
Epilobium glandulosum var. adenocaulon 
Uippuri.8 vulgaris 
Sium suave 
Mentha canadensis var. glabrata 
Stachys scopulorum 
Senecio palustria 
The shore section at the Government Hay Camp (Figure 12, A) was 
made at a low T -water stage when a wide, barren mud flat was exposed 
between the river and the first vegetation. The characteristic terrace 
formation is evident though low in relief, and in this case is caused by a 
minor slackening of currents below the rocky point shown on the map 
(Figure 13) . Further notes on the development of the Hay Camp area will 
be found in another part of the paper. The lower ground has an open 
association of Equisetum palustre, which trails over the mud on a terrace 
about 30 feet wide, reaching its greatest abundance at the landward margin. 
Primary sp.: Equisetum palustre 
Secondary spp.: Equisetum arvense 
Eleocharis calva 
J uncus nodosus 
Salix interior var. pedicellata (seedlings) 
Rorippa palm iris (seedlings) 
