SYMPOSIUM OX COXSERVATION 7I 



Doubtless the mere mentioning of the improvement of native 

 plants suggests to the minds of each one of you some wild plant 

 which you have observed and thought to possess valuable quali- 

 ties. If our sources of nitrogen supply are to be exhausted soon, 

 we must cultivate more leguminous crops which can gather their 

 own nitrogen and improve the soil in this respect while furnish- 

 ing crops. We should have leguminous tuber crops to take the 

 place of potatoes, beets and turnips. Nature has given us such 

 wild legumes as the ground nut (Apios tuberosa) and the Pomme 

 de Prairie {Psoralca esculenta), which already have edible tubers, 

 and which could doubtless be developed into very valuable culti- 

 vated plants by a few years of breeding. 



Dr. J. Russell Smith,^ of the University of Pennsylvania, has 

 emphasized the importance of breeding tree crops, and here we 

 have an inexhaustible field of experimentation. We should breed 

 chestnuts, walnuts, hickories, oaks, beeches, hazelnuts, and the 

 like, to improve them for the use of man and for growth as stock 

 food. Many hundreds of thousands of acres of rough, hilly 

 land, unadapted for cultivation, would be suited for the growth 

 of such crops. 



The possibilities of breeding tree crops are well illustrated by the 

 excessive increase in \*igor, rapidity of growth and size of fruit 

 obtained by Burbank in a hybrid between the English walnut {Ju- 

 glans regia) and the California black walnut (/. californica) . "The 

 hybrid," Burbank states, "grows twice as fast as the combined 

 growth of both parents. The leaves are from two feet to a full 

 yard in length. The wood is compact, with lustrous, silk)- grain, 

 taking a beautiful polish, and as the annual layers of growth are 

 an inch or more in thickness and the medullary rays prominent, 

 the effect is unique.'' Another of Burbank's walnut hybrids, 

 obtained by crossing the black walnut with pollen of the Cali- 

 fomian black walnut, produces fruit of very much larger size 

 than either parent, ^^'hen we come to plant large areas to trees, 

 as we are rapidly coming to do, imagine the immense value to 

 the world if we could plant hybrids of rapid growth, such as 

 Burbank's walnuts. 



Who has tried to produce hybrids of maples, oaks, hickories, 

 and pines, to get quick-growing hybrids for planting purposes? 

 Who has hybridized such trees to get larger and better fruits? 

 The world should not be compelled to w^ait much longer for 



^ Smith, J. Russell. The Breeding and Use of Tree Crops. American Breeders' 

 .Association, Vol. I, p. 86. 



