470 BURBANK'S PRODUCTION OF HORTICULTURAL NOVELTIES. 



what is to live and what is to be rejected. It is a well-known fact, 

 discovered by Koelreuter and Gartner, and confirmed by numerous 

 other scientific hybridologists, that hybrids often surpass both 

 their parents in the vigor of their growth and the profuseness of 

 their flowering. Taking advantage of this rule, in more than one 

 instance, Burbank has produced hybrids of extreme capacities. 

 The most astonishing instances are afforded by his hybrid walnuts. 

 In the year 1891 he crossed the English walnut and the Calif ornian 

 black walnut and afterwards planted a row of them along the road 

 before his residence. At the time of my first visit six gigantic trees 

 were seen growing. They had reached twice the height and size of 

 ordinary walnut trees. Three of them he has since been compelled 

 to cut down, because they increased too rapidly. This summer 

 (1906) I saw the three remaining specimens, eighty feet in height 

 and two feet in diameter. He showed me sections of the cut stems. 

 Their wood was of a fine grain, very compact and of silky appea- 

 rance. The annual layers measured 5 centimeters, a most extra- 

 ordinary thickness. Fast growing trees are usually of soft grain, but 

 these hybrid walnuts have a wood as hard as that of the ordinary 

 species. By recrossing them the qualities of the wood have been 

 still further improved, and selection in this direction produces a 

 broad variety of hard and soft, coarse and fine, plain and beautifully 

 marked, straight and wavy grain. In driving me to his Sebastopol 

 farm, he pointed out an enormous walnut tree in one of the gardens 

 along the road. It far surpassed all the surrounding trees, though 

 many of them were older. It is a hybrid between the native Cali- 

 fornian black walnut and the New England black walnut. It is, 

 next to the redwood and big trees, perhaps, the largest tree and 

 fastest grower I ever saw. 



Another tree which displays the vigor of hybrids is the Wickson 

 plum. It is a little more than ten years since Burbank distributed 

 the first grafts of this variety, and it was the first of his plums 

 to make a deep impression on California fruit growers. It was pro- 

 duced by crossing the above-named Burbank plum with the Kelsey, 

 both parents being varieties of the Japanese Prunus triflora. The 

 flesh of the Burbank is red, that of the Kelsey being dull pink and 

 green. The special merit of the breeder lies in the choice of the 

 parents from which to produce his hybrid. The Wickson plum is, 

 at present, most largely grown in California for shipping purposes 

 on account of its high durability. It has the unique heart shape 

 of the Kelsey but the flesh of the Burbank, a rich garnet and yellow 



