PROPAGATION BY CUTTINGS. 



351 



into lengths before flowering, and placed under 

 a hand-glass in a shaded border, root freely. 



Cuttings of leaves. — Some idea of this mode of 

 reproduction was entertained about the begin- 

 ning of the last century, as in a work in Dutch 

 by Agricola we find copperplate illustrations 

 showing whole fields covered with orange leaves 

 represented as growing into trees. Although 

 this is sufficiently absurd, still a knowledge of 

 the fact that some plants will strike roots from 

 their leaves must have been possessed. The 

 leaves of the orange, aucuba, and the fig, being fur- 

 nished with adventitious buds, will multiply in 

 this manner, as will also most of the genera Achi- 

 menes, Gloxinia, Gesnera, and many other plants 

 of like habit. Some of the Begonias, and many 

 succulents, do the same; and the old and much 

 neglected Bryophyllum 

 Fig. 125. produces abundance of 



young plants along the 

 margins of the leaves. 

 The process is as sim- 

 ple as the result is cer- 

 tain, and all that is re- 

 quired is to lay the 

 leaves fiat down on the 

 surface of silver sand, 

 keeping them in their 

 place by pegging them 

 down; or, better, lay- 

 ing a small stone upon 

 them, placing them in 

 heat, with a due 

 amount of moisture 

 and shade, as in other 

 cuttings : from the 

 veins a and crenate 

 notches b around their 

 edges, roots will speed- 

 ily issue, as shown in 

 fig. 125 ; and when form- 

 ed, the leaf, if it has not 

 rotted away, may be 

 torn up into pieces. 

 Sometimes the foot- 

 stalk of the leaf is 

 inserted in the sand as 

 if it were a cutting pro- 

 per, in which case an 

 excessive development 

 of cellular tissue takes 

 place at the base; a 

 callus is formed, from 

 which roots proceed, 

 fig. 126, and after- 

 wards a leaf-bud, which 

 forms the future plant. 

 " It is not surprising," 

 Dr Lindley remarks, 

 " that leaves should 

 possess this quality, 

 when we remember 

 that every leaf does 

 the same thing natur- 

 ally while attached to 

 the plant that bears 

 it ; that is to say, forms 

 at its base a bud which is constantly axillary to 

 itself." 



PROPAGATION BY 

 SINGLE LEAF. 



Fig. 12G. 



PROPAGATION BY LEAF. 



Besides the plants we have named above as 

 capable of propagating themselves by this means, 

 the following are given as examples by Professor 

 Balfour, in " Class Book of Botany :" " Some 

 leaves naturally produce buds on their surface, 

 as may be observed in M.alsixis,Aspidium bulbi- 

 ferum, and Nymphcea micrantha. Other leaves, 

 when placed in particular circumstances, give 

 rise to leaf-buds at their margin. Thus the 

 leaves of Bryophyllum callycinum, when placed on 

 the surface of damp soil, exhibit little roots all 

 round their edge. The leaves of Dioncea musci- 

 pula can also be made to produce buds, and so 

 can those species of Gesnera, Gloxinia, and 

 Achimenes. Occasionally leaves take root and 

 form plants, as was observed by Knight in 

 Mentha piperita. Buds are formed accidentally 

 on the leaves of Drosera, Portulaca, Cardamine 

 pvatensis, and Nepeta glechoma. They are also 

 formed on fleshy detached leaves, as on those 

 of different species of Crassula, Aloe, on the 

 bulb scales of Uucomis regia, Lilium candidum, 

 Hyacinth and Squill, and on the leaves of Orni- 

 thogalum thyrsoides. The leathery leaves of 

 Ficus elastica, Hoya carnosa, and of species of 

 Citrus, Aucuba, and Theophrasta, are occasion- 

 ally bulb-bearing." 



Bell-glasses and hand-glasses are placed over 

 newly-planted cuttings, with a view to preserve 

 a uniform degree of humidity in the atmosphere 

 by which they are surrounded, and to prevent, 

 by the almost exclusion of air, that draught 

 on the energies of the foliage which would take 

 place were they not protected from its action. 

 An excess of heat, cold, air, water, and even 

 light, are alike injurious to tender cuttings ; 

 and, therefore, to guard against these extremes 

 such coverings have been adopted. 



§ 6. — PKOPAGATION BY LAYEKS. 



Layering is one of the simplest, and probably 

 one of the most primitive of all modes of pro- 

 pagation. It consists generally in bending 

 down the branches of shrubs or trees which are 

 produced nearest the ground, and sufficiently 

 flexible for the purpose, so that a portion of 

 their length near to the middle may be covered 

 with earth, and so bent that the point of the 

 branch may be placed in a perpendicular direc- 

 tion. The object of layering is to multiply the 

 tree or plant without alteration in its character. 

 The result, however, often is that a tree origi- 

 nated by layering does not always assume the 

 robust and upright character of its parent, but 

 assumes that of a rooted branch, as is often 

 exemplified in the case of coniferous trees. 

 This may, however, be corrected by cutting over 

 the layer, after it is fairly rooted, near to the 

 ground, where some latent bud may spring, and 

 so send up a proper leader. It is also employed 

 in the case of plants which are difficult to 

 graft or bud, and which do not strike freely by 

 cuttings, or produce seeds in this country. 

 Herbaceous plants, such as the carnation, strike 

 root readily from layers, and make as good 

 plants as if propagated by any other means. 

 Hardy shrubs with long trailing branches, like 



