BURBANK'S HORTICULTURAL NOVELTIES 175 



ordinary species. Byrccrossing 

 them the quahtics of the wood 

 have been still further improved, 

 and selection in tliis direction 

 produces a broad variety of 

 hard and soft, coarse and hne, 

 plain and beautifully marked, 

 straight and wavy grain. In 

 driving me to his Sebastopol 

 farm, he pointed out an enor- 

 mous walnut tree in one of the 

 gardens along the road. It far 

 surpassed all the surrounding 

 trees, though many of them 

 were older in age. It is a hy- 

 brid between the native Cah- 

 fornia black walnut and the 

 New England black walnut. 

 It is, next to the redwood and 

 big trees, perhaps, the largest 

 tree and the fastest grower I 

 ever saw. 



Another tree which displays 

 the vigor of hybrids is the 

 Wickson plum. It is a httle 

 more than ten years since Bur- 

 bank distributed the first grafts 

 of this variety, and it was the 

 first of his plums to make a 

 deep impression on Californian 

 fruit growers. It was produced 

 by crossing the above named 

 Burbank plum with the Kelsey, 

 both parents being varieties of 



Fig. 56. Extreme variability 

 in tlie size of seedlings of hybrid 

 walnuts in the second generation. 



