PROPAGATION. 



235 



All plants which like plenty of moisture can be 

 multiplied by means of cuttings kept in moist 

 close conditions; plants which require a drier 

 atmosphere and plenty of air should, when in 

 the cutting state, be kept less close than the 

 former. We root a Cactus by drying it in the 

 sun, whereas the cuttings of a Begonia, Nepen- 

 thes, Bouvardia, Poinsettia, &c, must be kept 

 moist, close, and shaded. An excellent remedy 

 for 'damp', which often plays much havoc 

 among cuttings of soft-wooded plants, such as 

 Lobelia, Verbena, Viola, &c, is a weak solution 

 of permanganate of potash (Condy's Fluid), with 

 which the pots affected may be watered without 

 injury to the most delicate cuttings, and gener- 

 ally with the most curative results so far as 

 the ' damp ' is concerned. The solution when 

 mixed should be not darker than sherry. 



Light — Generally speaking, cuttings require 

 less light than is essential to the healthy growth 

 of rooted plants. An excess of sunlight induces 

 rapid transpiration and consequent weakness. 

 All cuttings should, however, have as much 

 light as they can well bear, and some will bear 

 much more than others ; thus, Pelargoniums will 

 strike well if exposed to the direct rays of the 

 sun, and so will many other plants of a succu- 

 lent nature. 



Bell-glasses (cloches). — These are among the 

 most useful of the appliances of the propagator, 

 and a supply of various sizes should always be 

 kept in readiness. It is surprising how many 

 plants may be propagated by means of cuttings 

 planted in a pot and covered with a bell-glass, or 

 in a shaded border and covered with a ' cloche \ 

 There are variously formed and tinted bell- 

 glasses to be had, the ordinary green-tinted bell 

 with a knob at the top being the cheapest and 

 most useful. Some propagators prefer the 

 white glass, and the knob at the top pierced 

 with a hole to let out excessive moisture. The 

 'cloche' is a large bell-glass much used by 

 market gardeners for sheltering delicate plants 

 as well as for protecting cuttings. It is advis- 

 able to stipple them with paint or any shading 

 mixture if intended for cuttings outside where 

 shade is needed. Flat-topped glasses are anti- 

 quated and not to be recommended for propagat- 

 ing purposes ; the dome top is preferable, as the 

 moisture condensed on the glass inside runs 

 down easily. Different coloured glasses have 

 been employed in France; according to Neu- 

 mann, blue and violet-coloured are preferred; 

 but in the climate of Britain the light is less 

 powerful than at Paris, and white or green- 

 tinted glass j s considered the best. 



VIII. — Propagation by Leaves. 



The first attempt on record to raise a tree 

 from a leaf was made by Mandirola, an Italian 

 horticulturist, whose mode of proceeding was 

 published by Richard Bradley in the beginning 

 of the last century. This mode of propagation 

 is now often advantageously practised for such 

 plants as the Gloxinia and numerous other 

 Gesneriads, Bertolonias, Begonias, Echeverias, 

 Pinguicula, &c. There is no physiological reason 

 why the leaves of all bud-producing plants should 

 not develop buds and roots under favourable 

 conditions. It is always worth while to try 

 them in the case of new and rare plants of 

 which a stock is wanted quickly. 



Roots and buds, it has already been stated, 

 derive their origin and their rudimentary sub- 

 stance, either directly or indirectly, from the 

 leaves. This being the case, it might be possible 

 to propagate most plants by their leaves, pro- 

 vided the latter could be kept alive, after being 

 detached from the stem, such length of time as 

 would allow of a sufficient quantity of cellular 

 tissue being elaborated and protruded from the 

 petiole, or from the section of the midrib, to 

 form granulated callosities for the production 

 of spongioles and adventitious buds. The leaves 

 of some plants, whilst not detached, return cel- 

 lular tissue abundantly to the roots by the 

 processes of digestion and continuous supply. 

 The crude sap which leaves are capable of con- 

 taining is in some quickly elaborated, and as 

 quickly replaced; so that, although all the sap 

 which such leaves contain at any instant may 

 afford but a very small quantity of matter avail- 

 able for the formation of roots and buds, yet, 

 when the supply is continuous, the amount may 

 be considerable in the course of several weeks. 



In selecting leaves to be used as cuttings 

 those that are either too young or too old are 

 not suitable. The energy of young leaves is 

 employed towards their own growth. Mr. 

 Knight, in his Physiological Papers, p. 34, states, 

 that "young leaves expend, in adding to their 

 own bulk, that which ought to be expended in 

 the creation of shoots". On the other hand, 

 leaves that are too old may be considered to 

 have performed their functions, or nearly so, 

 and therefore on the eve of becoming inactive, 

 or of entering into a state of decay. Leaves 

 that are full-grown are to be preferred: such 

 will generally be found in the middle part of 

 the shoot. Some recommend the petiole to be 

 inserted its whole length. M. Neumann cuts it 

 off nearly close to the base of the blade. The 



