52 AGRICULTURE FOR BEGINNERS 



the animal kingdom we have in the mule a common example 



of this cross breeding. Plant hybrids were formerly called 



mules also, but this suggestive term is now about out of use. 



It is only when plants of two distinct kinds are crossed 



FIG. 38. ORANGE BLOSSOM PREPARED FOR CROSSING 

 First, bud ; second, anthers unremoved ; third, anthers removed 



that the result is called a hybrid; for example, a blackjack 

 oak on a white oak, an apple on a pear. If the parent 

 plants are more closely related, as, for example, an apple of 



st... 



FIG. 39. TOMATO BLOSSOM READY TO CROSS 

 First, bud ; second, anthers unremoved ; third, anthers removed 



one kind with another variety of apple, the result is known 

 simply as a cross. 



Hybrids and crosses are valuable in that they usually 

 differ from both parents yet combine some of the qualities 



