378 THE ANATOMY OF WOODY PLANTS 



brought about by currents of air in some of the probably more 

 primitive groups. Fertilization is always porogamous (through 

 the micropyle), and chalazogamy is at the present time quite 

 unknown in the monocotyledons. The members of this group 

 are extremely important as food plants on account of their high 

 efficiency in the elaboration of assimilates. The proportion of 

 seed produced by some of the cereals in a vegetation period of 

 three or four months is often over 30 per cent of the total weight 

 a relative productiveness seldom realized in other plants. 



