INTRODUCTION 7 
Now the seeds of last year’s annuals, under the 
beneficent influence of the sun’s warm, energising 
rays, aided by the reserve material supplied to the 
embryo by the endosperm, begin to commence an 
entirely new phase. They begin to grow and to put 
forth their leaves, to attain a stem and branches, 
lengthened each day, and as time goes on they 
flower and exhibit their gay colours to attract the 
insect life upon which for perpetuation (¢.¢. ferti- 
lisation and seed formation) they are so largely 
dependent. Whilst some plants can, after self- 
pollination, fertilise and mature their seed without 
this friendly assistance, others cannot, hence the 
tempting store of honey and pollen which is offered 
so hospitably to the wandering bee or hovering 
butterfly has its meaning to us in the aid they 
render the flowers by making cross-pollination a 
possibility. 
In earlier phases of the earth’s history, if summer 
dawned at all, there were no winged honey-porters, 
and the wind (as now in the case of trees in spring 
and other dicecious flowers) alone carried out this 
needed office. 
The biennials, too, in their second season, begin 
during the summer to flower for the first time. Each 
summer month has its own particular flowers. Each 
flower requires its own particular amount of heat to 
come to maturity, to flower and to seed. Hence it 
is that all the flowers do not bloom at once. 
This variety of requirements is for us all the more 
