200 
GOTE TURESSON 
Having given a brief account of the nature and character of swamp 
and bog vegetation in this region we will now discuss in fuller detail 
the behavior of Lysichiton camtschatcense in sphagnum bogs. The 
bog in which the following observations have been made is that of 
Green Lake lying within the city limits of Seattle. Most of this bog, 
formerly about 12 hectares in extent, has been drained and turned 
into arable soil and only about 0.2 hectare now remain bearing the 
original bog vegetation. Rigg (21) has in his study of the toxic 
properties of waters from different sphagnum bogs of the region 
given a brief sketch of the flora of this bog. From the fact that the 
water from the bog had no toxic effect on the development of root- 
hairs in Tradescantia, probably on account of partial drainage, he 
concludes that plants not found in typical bogs had been able to enter 
and establish themselves. The flora is doubtless somewhat mixed 
in character. Figure 3 shows a part of the bog. Ledum groenlandi- 
cum dominates the area with Kalmia, Oxycoccus, and Drosera ro- 
tundifolia as secondary species. So far the flora is that of the typical 
sphagnum bog. However, in addition to the trees commonly found 
in peat bogs, namely Tsuga heterophylla and, in rarer cases. Thuja 
plicata, Picea sitchensis and Pinus monticola, we find Pseudotsuga 
taxifolia and Alnus oregona, and, among shrubs, Salix scouleri and 
Cornus occidentalis . The occurrence of these latter might be explained 
on the basis of partial drainage of the bog. The occurrence of Ly- 
sichiton in the bog requires, however, another interpretation. There 
is, furthermore, another peculiarity which in a still higher degree than 
the mere presence of Lysichiton demands an explanation. Holes of 
considerable depth and width are scattered all over the area. Ly- 
sichiton is strictly confined to these holes. Firmly rooted in the 
bottom it occupies most of the space by virtue of its large and numerous 
leaves which only partly reach out of the hole. In the following 
table measurements of a number of representative pits are given in 
centimeters, the width being that of the upper edge. 
The form of these holes is mostly circular and wider above than 
below. Figure 4 is a photograph of one of them in winter-time. 
Remains of last year's skunk cabbage leaves are seen at the left. 
The characteristic vegetation of Ledum, Kalmia and Oxycoccus sur- 
rounding the pit can also be seen. A further fact to be born in mind 
is that the hole sunk in the soft mass of Sphagnum has its sides covered 
not with a growth of Sphagnum but with a number of other mosses 
