General 
working green material per square foot of sunlight is 
almost incalculable. 
It enjoys, of course, maximum sunshine and ample 
moisture. When either of these factors is at all de- 
ficient, there is very much less complexity and far less 
exuberance of growth. 
In our own woods and forests, the most favoured 
places seldom possess more than three green layers. 
There is (1) the tree foliage; (2) an undergrowth of 
male and lady fern, with wood flowers such as Hyacinth ; 
and (3) a carpeting of feathery mosses * (Hylocomium 
and Hypnum, sp.). 
A very few years ago any scientific person, when let 
loose in such a botanical paradise as the tropical jungle 
of West Africa or Java, would do nothing but feverishly. 
collect and dry any flowers that he saw. He would be 
so entirely occupied, so thoroughly happy in the extra- 
ordinary profusion of flowers unknown to him, and very 
likely new species, that he would probably fail to see 
the “ wood” for the trees. 
Even to-day and in Great Britain, there is much to 
be discovered about the way of life of a “wood” con- 
sidered as a whole, and not as a catalogue of individual 
plants. 
Such plants as Foxglove and Raspberry, which spring 
up in extraordinary profusion when a wood has been 
felled, may be compared to the seed leaves or cotyledons 
of asingle plant. They are apt to vanish when the wood 
begins to reform itself. But they are of some use to it, 
for two or three years’ growth of these forerunners cover 
the soil with rich layers of leaf mould and utilise a// the 
sunshine that falls upon the surface during those years. 
* Five leaf-surfaces are said to exist in many tropical jungles, but the author 
has seldom seen more than four. Often they are so jumbled up as to be quite 
indistinguishable. 
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