AND HIS PLANT SCHOOL 51 



make the blooms larger, change their color, lengthen or 

 shorten the stem, and make many other changes. Did you 

 ever see a bleeding heart that was not a pink red? Prob- 

 ably not, but Burbank 

 has produced one that 

 is white. 



This changing process 

 can sometimes be great- 

 ly hastened by crossing 

 two plants which are 

 closely related but have 

 different qualities, un- 

 like in size or color. 

 To understand what is 

 meant by crossing, you 

 must understand some- 

 thing about the parts 



of a flower and the uses 



r , _ White bleeding heart, 



of these parts. Every 



complete flower has sepals, petals, stamens, and a pistil, 

 and several pollen-bearing anthers. 



Each outer leaf is called a sepal. Sepals are more com- 

 monly green or greenish, but not always. 



Each inner leaf is called a petal. Petals are usually of 

 some other color than green, and form the showy part of 

 the flower. 



The stamen bears on its stalk a little powder box filled 



