BALSAM FIR. 
uted to two causes, excess of moisture and a short growing season. 
The dense evergreen foliage of the coniferous trees, as well as the 
ground cover of moss, shields the ice which forms in the ground 
during winter against the rays of the sun in the spring. Thawing, 
and therefore the root activity of the trees, begins later in the swamps, 
often five weeks, than on the slopes or dry flats. 
The characteristic ground cover of balsam swamps is made up of 
mosses, which form about 70 per cent of the herbaceous vegetation. 
The character of the vegetation and the relative proportion of the 
different species which compose the ground cover of the swamps is as 
follows : 
Mosses (70 per cent): 
Common- 
Sphagnum. 
Fern moss (Hylocomuim proliferum). 
Shaggy moss (Hylocomuim- Iriquitrum). 
Scale moss. 
Occasional- 
Crane moss (Dicranum fuloum). 
Fern and fern allies (10 per cent): 
Common— » 
Spinulose shield fern (Dryopteris spinulosa). 
Cinnamon fern (Osmunda oinnamomea).. 
Lady fern (Asplenium felixfemina). 
Long beech fern (Phegopteris phegopteris). 
Oak fern (Phegopteris dryopteris). 
Marsh shield fern (Dryopteris phegopteris). 
Crested shield fern (Dryopteris cristata). 
Sensitive fern (Onoclea sensibilis). 
Rare— 
Fernata grape fern (Botrychium obliquum). 
Horsetail (Equisetum sylvaticum). 
Flowering plants (20 per cent): 
Common- 
Wood sorrel (Oxalis acetosella). 
Gold thread ( Coptis trifolia). 
Bunchberry ( Cornus canadensis). 
Dalibarda (Dalibarda repens). 
Flowering plants (20 per cent)— Continued. 
Common— Continued . 
Sweet white violet( Viola blanda palustriformis). 
Creeping snowberry ( Chiogenes Jnspidula). 
Clintonia ( Clintonia borealis). 
Wild sarsaparilla (Araua nudicaulis). 
Twin flower (Linnaea oorealis). 
Occasional— 
Chickweed wintergreen ( Trientalis americana). 
Painted trillium ( Trillium undulatum). 
Two-leaved Solomon's seal ( Unifolhim cana- 
dense). 
Rare- 
Creeping wintergreen (Gaultheria procumbens). 
Indian pipe ( Monofropa uniflora). 
Underbrush: 
Common- 
Green alder (Alnus alnobetula). 
Mountain ash (Pyrus americana). 
Withe rod ( Viburnum cassinoides). 
Occasional — 
Mountain holly (Ilicioides mucronata). 
Fetid currant (Ribes prosiratum). 
Swamp honeysuckle (Lonicera oblongifolia). 
Pale laurel (Kalmia glauca). 
Mountain maple {Acer spicatum). 
Hobble bush ( Viburnum alnifolium). 
FLAT. 
The flat type is intermediate between the swamp and the hard- 
wood slope. It includes the low swells adjoining wet swamps, or 
the gentle lower ridges, and also the knolls in wet swamps. It is 
fairly well drained, and fern moss replaces sphagnum as the principal 
ground cover. In essentials it is still the swamp, except that it is 
drier. Lumbermen, in fact, call it "dry swamp." Here balsam 
grows rapidly, becomes tall, straight, and clear-boled, attains a fair 
diameter, and, as in the swamp, often grows pure. But the trees 
in the dry swamp are much more subject to ground rot than in the 
wet swamp. When it occurs in mixture its associates are red spruce, 
yellow birch, and red maple — the two latter small and unimportant. 
It is on the flats that the heaviest stands of balsam fir are found, 
and here also it grows more commonly in mixture with red spruce, 
with which it is cut and marketed for the same uses. Of the four 
types, therefore, the flat is commercially the most important. 
