This section is from the book "Commercial Gardening Vol1", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
Many Ferns, including a large number of Aspleniums (fig. 46), Bryophyllum calycinum (tig. 46), Tolmicea Menziesii, Cardamine pratensis, and its double variety naturally produce buds on the margins, base, or upper surface of their leaves, which grow into plants under conditions favourable to the production of roots. The leaves of Begonia Rex and its varieties may be induced to form buds artificially by cutting through the thick ribs, laying the leaves on sand, pegging or fastening them in position in a moist, warm frame, till small tubers bearing a bud are formed. On the other hand, those leaves may be cut into strips, each with a thick rib, and inserted as cuttings in sand. Leaves of Gloxinias, Streptocarpus, and allied plants may be dealt with in the same way. The fleshy leaves of Cotyledon (Echeveria), Semper-vivum tabulceforme, and the bulb scales of many Lilies and Hyacinths may be pulled off in their entirety and laid on sand, kept moist, or lightly dibbled into the sand, and they will form small or young plants. Lastreas, Scolo-pendriums, and other ferns often form a small plant at the base of the leaf stalk, or may be induced to do so by inserting the thick base in sand and keeping it moist. Reserve materials are present in all these cases, together with a plentiful supply of water within the tissues, and this serves to keep the leaves alive and carry the food materials to the point where a tuberous callus is formed, from which the roots are emitted. The leaves of the Cotyledons have a cuticle as well as a layer of wax, which prevents the escape of their sap, and they must not be kept wet by too frequent watering, or they will damp off. It is possible that most leaves could be rooted in this way if they could be kept alive without damping till roots are formed.
All the above are methods of vegetative or asexual reproduction, and their object is to multiply the plant and keep varieties true to character and name. They furnish a means of increase where no seeds or spores are obtainable, or might not come true to the parent, and in the case of choice and rare ferns may be the only means of perpetuating them. None of the above processes gives rise to a new individual, but merely young or rehabilitated pieces of the old ones, and this is what vegetative reproduction implies. [J. f.].
Fig. 46. - Formation of Buds on Fronds and Foliage Leaves.
1, 2, on the pinnules of Asplenitim bulbiferum; 3, on the margins of the lobes of the leaves of Bryophylhim calycinvm.