Book IV. PROPAGATION BY LAYERING. 389 



has not, we think, been yet determined, but its effects have long been very well known 

 to gardeners. In all cases the layer must be held firmly in its place by hooked pea's. 

 The operation of layering is performed on herbaceous plants as well as trees; and 

 the part to become the future plant is, in both cases, covered with soil about a third of 

 its length. 



1996. Layering by twisting, ringing, piercing, and wiring the shoot intended for the 

 future plant is also occasionally practised. 



1997. Piercing is performed with an awl, nail, or penknife, thrust through two or 

 three times in opposite directions at a joint ; from which wounds, first, granulated matter 

 oozes, and finally, fibres are emitted. 



1998. Bmging is cutting off a small ring of bark and part of the wood, by which the 

 return of the sap being wholly prevented, it is, therefore, as it were, compelled to form 

 roots. Care must be taken, however, that the ring does not penetrate far into the wood, 

 otherwise the sap will be prevented from ascending in the first instance, and the shoot 

 killed. 



1999. Wiring is performed by twisting a piece of wire round the shoot at a joint, 

 and pricking it at the same time with an awl on both sides of the wire. It is evident 

 that all these methods depend on the same general principle, that of permitting the ascent 

 of the sap through the wood, but checking its descent by cutting off or closing the vessels 

 of the bark. 



2000. Layers which are difficult to strike may be accelerated by ringing. Rino-incr i s 

 an excellent method for making layers of hard-wooded plants strike root with Greater 

 certainty, and in a smaller space of time than is attained in any other way. The°accu- 

 raulated vegetable matter in the callus, which is formed on the upper edge of the rino- 

 when brought into contact with the soil, or any material calculated to excite vegetation, 

 readily breaks into fibres and roots. (Hort. Trans, iv. 558.) 



2001. Ln layering trees in the open garden, whatever mode be adopted, the ground 

 round each plant intended for laying, must be digged for the reception of the layers ; 

 then making excavations in the earth, lay down all the shoots or branches properly 

 situated for this purpose ; pegging each down with a peg or hooked stick ; laying also 

 all the proper young shoots on each branch or main shoot, fixing each layer from about 

 three or four to six inches deep, according as they admit, and moulding them in at that 

 depth, leaving the tops of every layer out of ground from about two or three to five or 

 six inehes, according to their length, though some shorten their tops down to one or two 

 eyes. Observe also to raise the top of each layer somewhat upright, especially tongue or 

 slit layers, in order to keep the slit open. As the layering is completed, levelfin all the 

 mould finally, and equally in every part close about every layer, leaving an even, smooth 

 surface, presenting only the tops of each layer in the circumference of a circle, and the 

 stems or stools in the centre. Sometimes the branches of trees are so inflexible, as not 

 to be easily brought down for laying; in which case they must be plashed, makino- the 

 gash or cut on the upper side ; and when they are grown too large for plashing, or'that 

 the nature of the wood will not bear that operation, they may be thrown on their sides, 

 by opening the earth about their roots, and loosening or cutting all those on one side,' 

 that the plant may be brought to the ground to admit of laying the branches. 



2002. Layering plants in pots. When layers are to be made from green-house shrubs 

 or other jrfants in pots, the operation should generally be performed either in their own 

 pots, or in others placed near that of the stool to receive the layer. 



2003. General treatment. After laying in either of the above methods, there is no par- 

 ticular culture requisite, excepting that of keeping the earth as much as possible 

 of uniform moisture, especially in pots ; and watering these in the open air in dry 

 weather. 



2004. Management of stools. When the layers are rooted, which will generally be the 

 case by the autumn after the operation is performed, they are all cleared from the stools 

 or main plants, and the head of each stool, if to be continued for furnishing layers, should 

 be dressed ; cutting off all decayed and scraggy parts, and digging the ground round 

 them. Some fresh rich mould should also be worked in, in order to encourage the 

 production of the annual supply of shoots for layering. 



2005. C/iinese laying. The Chinese method of propagating trees by first ringing, or 

 nearly so, a shoot, and then covering the ringed part with a ball of clay and earth, 

 covered with moss or straw, is obviously on the same general principle as layering ; and 

 is better effected in this country by drawing the shoot through a hole in a pot (such a 

 pot as Jig. 175.) ; ringing it to the extent of three fourths of its circumference, near the 

 the bottom or side of the pot, and then the pot, being supported in a proper position, and 

 filled with earth, it may be watered in the usual way. Some plants difficult to strike, 

 and for which proper stocks for inarching are not conveniently procured, are thus pro- 

 pagated in the nursery hot-houses. 



2006. Removal of the rooted layer or plantlet. Though layers of trees completed early 



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