268 



PROPAGATION BY LEAVES. 



cuttings had become beautiful and healthy plants, which it was impossible to 

 distinguish from others produced from entire leaves. 



We see from this experiment that it requires double the time to produce 

 a bud from the upper part of a leaf, that it requires for the lower half to 

 produce one ; and that, in propagations by leaves, it is not always necessary 

 to take the heel or lower end of the petiole with the leaf, which sometimes 

 injures and deforms the shoots. M. Neuman's experiment proves further, 

 that wherever cambium can be formed, there are at 

 the same time a number of utricules or germs of 

 buds formed, from which a new plant will be deve- 

 loped when the parent is 

 placed in favourable circum- 

 stances. From this circum- 

 stance, in short, we may 

 conclude that all the veins 

 ma^ serve for the reproduc- 

 tionjof plants. The dots in 

 fig 179 show the parts of the 

 upper half-leaf which were 

 cut off to allow of its being 

 put into a small pot; and 

 this proves that it is only the 

 Fig. 178. The lover W of the middle rib (or prolongation of 



leaf of theophrasta rooted and the petlole),which IS required Fig. 179. The upper half of 

 sending up a shoot. f or reproduction. Half leaves f/ie P>' r <*s f a rooted and tend. 



, , , T . i i . * n 8 up a thoot. 



of various plants have been rooted m charcoal in 

 Germany (603). 



612. The plants usually raised by leaves in British gardens are comparatively 

 few, and chiefly gesneras, gloxinias ; bulb-bearing leaves, such as br^ophyl- 

 lum; some succulents, such as sempervivum, and a few others. Leaves of the 

 orange, the hoya, the aucuba, the camellia, ficus elasticus, the clianthus, the 

 common laurel, and a few more, are occasionally rooted, but more as 

 matter of curiosity than for the purpose of increase. 



613. Propagation by the leaves of bulbs has been successfully effected by the 

 Hon. and Rev. W. Herbert, who first tried it, in 1809, by setting a cutting 

 of a leaf of a Cape Ornithogalum. " The leaf was cut off just below the 

 surface of the earth in an early stage of its growth, before the flower-stalk 

 had begun to rise ; and it was set in the earth, near the edge of the pot in 

 which the mother plant was growing, and so left to its fate. The leaf 

 continued quite fresh, and on examination (while the bulb was flowering) 

 a number of young bulbs and radical fibres were found adhering to it. 

 They appeared to have been formed by the return of the sap which had 

 nourished the leaf. Thereupon two or three more leaves were taken off 

 and placed in like situations ; but they turned yellow, and died without 

 producing any bulbs. It appeared to me then, and it was confirmed by 

 subsequent experience, that in order to obtain a satisfactory result the leaf 

 must be taken off while the plant is advancing in its growth. I found it 

 easy thus to multiply some bulbs that did not willingly produce offsets. 

 I afterwards tried, without cutting the leaf off, to make an oblique incision 

 in it under ground, and in some cases just above ground, attempting, in fact, 

 to raise bulbs by layering the leaf. This attempt was also successful, and some 



