LAWSONIA 



LAYERS 



1831 



fls. ; otherwise they are rose, an L. rubra is listed, and 

 var. miniaia, Hassk., is cinnabar-red. Widely cult, in 

 tropical countries, but probably native in N. Afr., 

 to W. and S. Asia; naturalized in W. Indies, where it is 

 known as "mignonette." Its Ivs. produce the henna or 



TREES AND SHRUBS 



VINES AND CANES 



Bowed branch 



Bark ruptured. 



Bark ringed. 



Tongue cut. 



Tip layered. 

 Mound- or stool-layer. 

 Potted or aerial layer. 



i Simple layer. 

 < Trench layer. 

 (Serpentine layer. 



2118. A layer notched at the bottom. 



2119. A layer ringed or girdled at the bottom. 

 For many 



alhenna of the Arabs (cyprus of the ancients), a yellow 

 dye which is used in Egypt and elsewhere by women to 

 color their nails, and by men to dye their beards, and 

 for other similar uses. It is also known in W. Indies as 

 "Egyptian privet," and sometimes as "reseda." It 

 is the camphire of the authorized version of the Bible. 



L. H. B. 



LAYERS, Propagation by. A layer is a stem that is 

 made to take root while still attached to the parent 

 plant. The whole subject of propagating plants by 

 means of layers is known as layerage; the actual opera- 

 tion or practice is layering. 



The tendency, under favorable conditions, to pro- 

 duce roots from the cambium zone of some part of the 

 stem is manifested by many plants, especially in the 

 tropics. It may be noticed in the species of ficus culti- 

 vated in the greenhouse, in epigaea and Rhus Toxicoden- 

 dron in the woods, in tomato vines in the garden, in 

 grape-canes lying on the ground, and frequently in 

 young apple trees when the trunk becomes covered with 

 earth to an unusual depth. With most such plants, root- 

 ing by detached parts is easily accomplished, and this 

 being more convenient, layering is usually practised only 

 with those plants that do not root readily from cuttings. 

 The mode of root-production is essentially the same 

 whether the part is a layer or a cutting. The proper 

 conditions as to moisture, temperature, food-supply, 

 seem to stimulate the formation of one or more grow- 

 ing points in the cambium zone. The multiplying cells 



force their way through 

 the bark, and if favor- 

 able soil contact is 

 secured, supporting roots 

 are soon developed. It is 

 when the food supply is 

 deficient or the cell action 

 is so slow that the de- 

 tached part will perish 

 before supporting roots 

 can be established, that rooting while the parts are still 

 attached to the parent plant and nourished by it need 

 be employed. 



The different methods of layering are matters of 

 detail adapted to the varying plants to be dealt with. 

 Usually branches are chosen of rather young wood, 

 which can easily be brought under the soil and which, 

 when rooted, can be removed without damage to the old 

 plant. The most favorable season is usually the spring 

 or time of most rapid cell-growth. The methods of layer- 

 ing may be represented in the following diagram: 



As shown in Fig. 2118, a suitable branch is bent to the 

 ground and held in place by a forked pin, so that a part 

 of it is covered with 2 or 3 inches of rich earth, the end 

 being bent to an upright position and fastened to 

 a stake. The bend and consequent rupture of the 

 bark may be all that is needed to obstruct the 

 movement of food-material and cause the develop- 

 ment of roots at this point. If not, a tongue may 

 be cut not deeper than one-third the 

 thickness of the branch from below 

 upwards and near a bud or node. In 

 Fig. 2119 a layered branch is shown 

 with a ring of bark removed, a good 

 practice with thick hard -barked 

 species. 



i-vji many low-branched shrubs, mound- or stool- 

 layers are prepared (Fig. 2120), as follows: In the spring, 

 head the bush back to a series of stubs, which will pro- 

 duce a large number of vigorous young shoots. By 

 midsummer, in some cases, or the following spring, a 

 mound of earth is thrown around the old stool and the 

 base of the new shoots, and from these latter abundant 

 rooting is secured, so that by the following autumn or 

 spring they may be separated and set in nursery rows. 

 Dwarf apple stocks, and English gooseberries, are 

 propagated extensively by means of mound-layers. 



When a branch cannot be brought to the ground, 

 sometimes the earth is brought to the branch by clasp- 

 ing the halves of a broken or specially made pot around 

 a tongued or girdled branch. The receptacle is filled 

 with earth and sphagnum moss to retain the moisture; 

 or the moss may be held in place by a cone of strong 

 paper (Fig. 2121). It may be necessary to support 

 the pot with a light stand of stakes. Where a moist 

 atmosphere is retained, as in a conservatory, merely a 

 ball of sphagnum bound around the branch with twine 

 will serve an equally good purpose with less trouble. 

 This kind of propagation is known as air-layering, 

 Chinese layering or circumposition. 



2120. Mound- or stool-layering. 



2121. Air-layering. 



