The Struggle for Life in the Swamp. 245 
butter-cups otten gives the effect of a yellow lane for 
miles. 
This last plant shows the transition stage to those 
which, like the water-lilies, float on the surface. As 
long as it is under water only delicate feathery foliage 
is produced, but it develops when on the surface pretty 
flat shield-like leaves. Here we see similar contrivances 
to those of trees in the forest and the swamp. As long 
as they are in water they spread out in every direction 
like the feathery leaves of the Cabomba, but when in the 
forest extend to form a thick and almost flat disk. 
With all their weakness these feathery water plants hold 
their own, and rarely are two species found growing to- 
gether. It may be that the tangle occupies the water to 
the exclusion of everything else, or perhaps all save the 
one species have been smothered by shutting out the 
light. 
Now we come to a class which does undoubtedly 
prevent everything from growing but themselves; Who- 
ever has seen an estates' canal covered with Victoria 
Regia must see thai every leaf is fighting for itself after 
it has smothered ail the other water plants. Take for 
example a newly-cleaned trench where this plant has 
been growing. At first it is quite free from weeds, but 
frequently a film of what looks like a reddish scum forms 
on the surface. This is the Azolla, and is well worthy of 
attention from its peculiar manner of growth, as well as 
its extreme prettiness. Then comes the Salvinia, and 
little later perhaps the silvery green rosettes of Pistia 
stratiotes. By this time a few Victoria leaves are open- 
ing and soon one leaf-bud comes up after another, 
covered with their network of ridges which entangle 
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