ASEXUAL PROPAGATION OF PLANTS ON OWN ROOTS 59 



tuber is cut off so as to contain one or more eyes, and is 

 planted, new individuals result. The Irish potato may be 

 propagated in this way. 



85. Root-cuttings. Plants which naturally produce suck- 

 ers 1 from the roots or which have the power of producing 

 adventitious 2 buds from the roots can be prop- ~ 

 agated successfully by root-cuttings. The black- 

 berry (Fig. 34), red raspberry, horse-radish, and 

 Rosa rugosa are propagated commercially in 

 this way. Many other plants, among them 

 willows, poplars, osage orange, juneberry, plums, 

 and cherries, can be propagated by root -cut- 

 tings, although most of these are reproduced 

 more easily by other methods. 



Roots for cuttings should be neither too large 

 nor too small. As a rule, they should be at 

 least as large as a lead pencil, but not over 

 three-fourths of an inch in diameter. They are Fl cut 3 ttn7?f t he 

 cut into lengths varying from one to four inches. 

 Root-cuttings may be stored in sand, and kept moist in a 

 cool place until they form a callus. In the spring they may 

 be removed and planted out-of-doors. Root-cuttings of 

 plants which thrive in cool climates, such as blackberries, 

 roses, and lilacs, can usually be grown out-of-doors. The 

 more tender plants require bottom heat. In any case bot- 

 tom heat hastens callusing. When root-cuttings are planted 

 out-of-doors, the soil should be pressed down over them 

 firmly but they should not be covered too deeply, seldom 

 over an inch. The cuttings must have moisture and in many 

 cases must be shaded. Root-cuttings produce plants true to 

 variety with the exception that they, like leaf-cuttings, 

 frequently do not transmit variegations. 



1 Sucker is the shoot of a plant from the roots or lower part of the stem; 

 usually very rapid in growth and unfruitful. 



2 Adventitious (as a botanical term) means out of the proper or usual place. 



