Flowers 
There are some interesting cases which show how 
co-operation prevails between leaves and flowers, or 
even amongst the flowers themselves. 
In the gorgeous Bougainvillea, a great favourite in 
tropical and sub-tropical gardens, it is the bracts that 
are flaringly conspicuous, but even more interesting is 
the common bluebeard salvia of our own borders, A 
fine dark blue has appeared in the uppermost leaves, 
which are of course most exposed to the sunshine. 
The actual flowers are small and provided with light- 
blue patches and yellow hairs. This is an ingenious 
effort towards both economy and efficiency, for the 
flowers are short-lived, whilst the large attractive leaves 
last during the whole season. 
A tropical orchid (Renanthera Lowii) has a different 
arrangement. In each spray of flowers the two upper- 
most are a bright sulphur-yellow with red dots or 
splashes upon them. These two have a very strong 
scent and last for a very long time. The other flowers 
are only white with brown dots ; they have no scent at 
all, and only live from seven to thirteen days. 
So the attractiveness of the two uppermost answers 
for all the others.’® 
It is of course to attract insects that these colours 
and perfumes have been so richly produced in nature. 
Aided bytheir ownexcessive respiration andhigh tempera- 
ture, and favoured by the sunshine, petals have formed 
all these exquisite shades and scents. But they have 
been from the beginning favoured and guided by the 
more inquisitive and therefore more intelligent of the 
insect-world. 
In the gloomy, misty atmosphere of the coal-measure 
swamp-forests, not very clever insects would surely fly 
to the yellow spores of the fern-seed plants, and no 
doubt eat the spores. 
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