PROPAGATION 69 



all depend on getting the cambium layer and a small portion, 

 at least, of the phloem and the xylem in such close contact 

 that the new growth will form a union through which food 

 and water will be translocated. For this reason, only plants 

 with a well-developed cambium are grafted, usually woody 

 plants. The scion carries the variety of plant, or we may say 

 the protoplasm which we want in the new plant, and there- 

 fore always remains like the original plant, while the stock is 

 usually chosen because of its vigorous or disease-resisting 

 root system. Grafting is usually done near the end of the 

 dormant season. Care must be taken to avoid the loss of 

 moisture from the scion before or after grafting. Grafting 

 wax is often used to cover the wounds of the scion and stock 

 to prevent drying. 



Grafting is used for many reasons: (1) it is a very com- 

 mon nursery practice because it offers a simple means of 

 enormously rapid propagation of a good variety. Many of 

 our best fruits have come from a single tree and in some cases 

 from a single bud sport of a tree. (2) A plant breeder work- 

 ing with tree fruits can cross the flowers; then he can plant 

 the seeds and after one year's growth use the whips as scions 

 and graft them on an older tree. In this way they will bear 

 fruit in less than half the time necessary for the growth of a 

 tree and much space is saved. (3) It enables people with 

 limited space to have as many varieties of apples, pears, or 

 cherries on a single tree as they wish. It has been reported 

 that Burbank had more than six hundred of such grafts on 

 a single plum tree. (4) The fruit of an older tree may be 

 changed to a more desirable variety by grafting on a number 

 of its branches. 



Root, tongue, or whip grafting is done by selecting the 

 stock and the scion of nearly equal diameter and cutting with 

 a sloping cut, about an inch long, then splitting each longi- 

 tudinally so that they fit together, after which they should be 

 bound snugly with waxed thread to hold them in place until 



