118 Gardening 
The pollen grain must reach the pistil when both 
are in the right condition or the pollen will not grow; 
Fic. 70. Stages of growth in the 
fruit (pods) of the bean. 
the ovules will not be fertilized, and no 
fruit or seed will be produced. A pol- 
len tube fertilizes only one ovule, and so 
at least as many different tubes must 
grow down through the pistil as there 
are seeds which develop later. 
During fertilization the egg cell and a 
sperm cell combine and make one cell. 
This new cell begins to grow and 
divide, and this growth is kept up until the embryo is 
formed. Meanwhile, the ovule develops into the seed, 
and the pistil enlarges to become the seed pod. 
Importance of the pollen parent. The little plants in 
the seeds borne by a bean plant all have the same mother. 
But the embryos in two seeds that lie side by side in 
the same pod may have different plants for pollen 
parents. If good and poor plants are allowed to bloom 
together, some of the seeds on even the best plants may 
