202 Principles of Plant Culture. 
nera and others, readily develop growing points of the stem 
and roots upon their leaves, a fact often turned to account 
in propagating these plants. Well-matured leaves, with the 
principal nerves cut across on the under side, are held in 
close contact with the surface of the propagating bed by 
pegging, or by light weights, or the leaf may be cut into 
pieces, which may be placed in the propagating bed and 
treated as ordinary green cuttings. 
ii 
Fi 
Fic. 102. Leaf of begonia on surface of propagating bed, giving rise to young 
plants. (After Bailey.) 
The leaves of the bryophyllum form rootlets and buds 
from the notches on their borders wherever these chance to- 
come in contact with a moist medium. 
b — Propagation by Grafting. 
383. Grafting consists in placing together two portions 
of a plant, or of different plants, containing living cambium 
tissue (69), in such a way that their cambium parts are main- 
tained in intimate contact. If the operation is successful, 
growth will firmly unite the two parts (70), and plant pro- 
cesses will go on much the same as if the parts had never 
been separated. The union usually takes place most rapidly 
when the cambium cells are in the state of most rapid divis- 
ion, i. e., when growth is most vigorous. 
