PROPAGATION BY LAYERS. 



277 



be enveloped in a mass of loam covered with moss, a mode practised by 

 the Chinese ; or with moss alone. The moss, in either case, may be kept 

 moist by suspending near it, and somewhat higher, a vessel of water with 

 some worsted threads, connecting the water with the moss, and acting as a 

 syphon. The threads ought to have small weights tied to their ends, in 

 order to keep them to the bottom of the vessel of water, in order that the 

 supply may go on as long as it contains any ; one thread will be enough for 

 every layer. This mode, however, in the present day is more a matter of 

 curiosity than of utility. Most plants when ringed beneath a joint will root 

 into moss alone, when placed in a warm moist atmosphere ; they will also 

 root in water when so ringed, provided the plant be in a growing state. 



629. The soil in which plants are layered should, in general, be that in 

 which the parent plants naturally thrive best, but with a mixture of sand, 

 or with the wounded part entirely enveloped in sand or powdered charcoal, 

 to prevent it from retaining too much water, which would prevent the wound 

 from protruding granulous matter, and cause it to rot. Plants which grow 

 in heath soil, such as most of the Ericace<Te, and aU other hair-rooted plants, 

 must be layered in sand or in heath soil, but almost all others will root 

 freely in sandy loam. Where the soil and the season are not naturally 

 moist, layers, even in the open garden, require artificial watering, or, at 

 least, are much benefited by it. Mulching may also be advantageously 

 employed in order to retain moisture. 



630. Hoohed pegs were formerly considered as essential articles for fixing 

 down the layers, but the general practice at present is to take a piece of the 

 shoot from the stool, or any waste piece of shoot about a foot in length, or 

 longer if the soil be very loose, and twisting it in the middle so as to prevent 

 it from breaking when bent, to double it like a lady's hair-pin over the 

 shoot, as shown at c, in fig. 183. The layers of herbaceous plants are 

 sometimes kept down by short loops of bass-mat put over them, and their 

 ends made fast in the soil with a small dibber. 



631. The time which layers require to produce roots varies in different 

 plants, from one to two, and even, in some cases, three or four years. The 

 process of rooting is facilitated by increased heat and moisture, and by ring- 

 ing below the tongue, or wounded or bent part from which the roots are ex- 

 pected to protrude ; but this operation can only be safely performed where 

 the parent plant is in vigorous health, because, otherwise, it would weaken 

 the root, and prevent it from sending up sap to nourish the layer. In taking 

 off layers which are difficult to root, it is a safe mode not to cut through the 

 layer at once, but by degrees, at intervals of several weeks. In the case of 

 stools in the open air the butt ends of the shoots from which the layers have 

 been taken are cut off close to the stool, to make room for a second succession 

 of layers, which are made annually from the upright shoots produced during 

 the preceding season. In the case of layers taken from plants in pots, the 

 stumps left after the layer is taken off should be cut to a leaf-bud, in order 

 that a shoot may be produced to supply the vacancy made in the head of the 

 plant by the removal of the layer. 



§ V. Propagation by suckers^ slips, offsets, runners, and simple division. 



632. A sucker is properly a shoot sent up from the under-ground part 

 of the stem, from latent buds there existing, or from adventitious buds on 

 that part of the stem, or on the horizontal roots. Those proceeding from 



