INTRODUCTION 5 
is a typical woodland of beech, the scrub and ground 
flora being often nil, as the shade is so dense. 
Tue FLOWERING SEASONS OF PLANTS. 
Something has already been said as to the influence 
of latitude upon the flowering seasons of plants in 
reference to the effect of climate upon plant habitats 
and distribution. 
Not only does the latitude cause a difference in 
temperature independently of the season, but the 
cycle of the seasons which is connected with the 
rotation of the earth and its revolution throughout 
the year round the sun has a similar effect. 
Owing to the rotation of the earth upon its axis 
and the demarcation of each twenty-four hours into 
day and night, the temperature is markedly different 
at alternate intervals of the twelve hours, when day 
and night are equal, whilst in Summer the length of 
daylight is much greater than that of the night. 
This proportion is reflected not only in the amount 
of total heat in each of the seasons, but also in the 
character of the season as one goes from the equator 
northwards, or to the land of the midnight sun. 
The four seasons recognised as Spring, Summer, 
Autumn and Winter again have marked character- 
istics, so that we can speak of Spring flowers, 
Summer flowers, Autumn flowers, Winter flowers. 
And these divisions of the year are each charac- 
terised by a difference in the amount of light, heat, 
