192 
GOTE TURESSON 
Alopecurus geniciilatus fulvus, Poa pratensis and Panicularia pauci- 
flora, have an abundance of Lysichiton. 
In order to make clear the relation of Lysichiton to the pond 
and swamp vegetation we have to outHne briefly the development 
and succession of the plant societies within the pond-swamp series. 
The only justification in dealing with this topic so often discussed 
lies in the fact that no data on the subject have appeared with refer- 
ence to Pacific coast conditions. 
It will be convenient to group the different types of vegetation 
belonging to the pond and swamp series under two heads, which we 
for want of better terminology designate as half-drained and un- 
drained ponds and swamps. Both types culminate in the coniferous 
climax forest, the former indirectly through a deciduous alnetum- 
salicetum, the latter without the intervention of a deciduous forest 
stage but through a typical sphagnetum. We find both types well 
represented in the Puget Sound region. As an example of the first 
type we may take Union Bay in Lake Washington. The well-known 
and much-discussed filling up process is going on here with Nym- 
phaea polysepala, Ceratophyllum demersum and Elodea canadensis 
as the principal soil formers among the aquatic species. Further 
inland follows the cat-tail Dulichium associations (Transeau 25) 
with Dulichium arundinaceum, Scirpus occidentalism Sparganium 
etirycarpum, and Typha latifolia. Back of this association and 
pushing forward often succeeding in reaching beyond it in places 
where the water is not too deep we have the two typical marginal 
plants Polygonum amphihium and Potentilla palustris fighting for 
supremacy and overrunning the somewhat earlier established, not 
seldom pure associations of Menyanthes trifoliata and Hippurus 
vulgaris. Next comes the shrub zone with Salix cordata, S. geyeriana, 
S. sitchensis, Spiraea douglasii and Myrica gale. There is often 
standing water between the thickets and pure associations of Myosotis 
laxa and Oenanthe sarmentosa. Encroaching upon this shrub zone 
we have the deciduous forest, almost exclusively made up of Alnus 
oregona. Salix lasiandra occurs in spots, and the characteristic shrub 
stratum is composed of Cornus occidentalis, Lonicera involucrata, 
Ruhus spectabilis and Sambucus callicarpa. Scattered trees of Thuja 
plicata give evidence of the advance of the coniferous climax forest 
on the deciduous forest. 
Lysichiton camtschatcense plays a prominent part in some of the 
