164 



PLANT rKOPAGATlON 



Funkia cases cited above, the anatomical cicatrization was effected by 

 the parenchymatic tissues. No hber or hbro-vascular structure was 

 observed to form between cion and stock. Thus the transport of 

 sap was hindered, and sooner or later both parts died. By util- 

 izing the aerial roots of some monocots to supplement the absorp- 

 tion of the cion, success was attained with several plants. This 

 shows that failure of grafts with monocots capable of regenerating 

 their tissues is due to insufficient vascular communication, since it 

 becomes possible when a complimentary apparatus is supplied. 



Plants with active cambium layers, which 

 may be inarched, cannot always be grafted by 

 the graft proper, since the common European 

 bean (Fabia) and the kidney bean, which graft 

 easily by approach, have always failed when 

 grafted by the graft proper, no matter what 

 precautions were taken. 



Differences in wood and bark are not ob- 

 stacles to success in the graft proper. Thus 

 there is a great difference in the thickness and 

 strength of safflower and annual sunflower; 

 between sunflower and Jerusalem artichoke; 

 young cabbage and root of turnip; root of 

 cultivated carrot and that of fennel; neverthe- 

 less, these [pairs of] plants united perfectly. 

 These same facts were observed with trees; 

 the graft succeeded between chestnut and oak, 

 pear and hawthorn, quince and hawthorn, in 

 spite of marked differences in the barks. From 

 these and other grafts it is concluded that hard- 

 ness, density, and elasticity of wood are second- 

 ary in the success and duration of grafts, but 

 it is not the same with conduction. 

 When the differences of sap conductions are too great, grafts will 

 not succeed; e. g., lilac and ash, cherry and almond, Cotoneaster 

 and chestnut, which grow the first year, then die without fructifying. 

 The duration of the graft is then very variable and depends for its 

 value on differences in conduction between cion and stock. Thus 

 pear grafted on quince endures for a shorter period than pear on 

 pear seedling [the Yeoman's dwarf pear orchard at Walworth, 

 New York, bore profitable crops for over 50 years! M. G. K,] 

 When the differences of conduction are too great between plants, 

 the mixed graft is sometimes used successfully where the ordinary 

 graft fails. By using it Daniel united Vcrnonia pracaUa and Xaii- 

 thium macrocarfum, which failed by ordinary grafting. 



Daniel has succeeded in grafting plants whose cell contents pre- 

 sented very marked differences; e. g., Chicoreaceas and Euphor- 

 biacese, which have different latex contents. Previously it had been 

 held that plants with milky juice could not be grafted. 



Grafts were made to determine what influence reserve material 

 in plants may have on grafting. The easy grafts on roots of car- 



FIG. 140— 



CUTTING ON 

 DAHLIA TUBER 



