The Rose: Its History, Poetry, Culture, and Classification, pp. 170-171 (1847)
Propagating Roses from Leaves
Samuel Browne Parsons

Some years since, Lecoq, a French cultivator, conceived the idea of endeavoring to propagate roses by the leaf. He gathered some very young leaves of the Bengal rose, about one quarter developed, cutting them off at their insertion, or at the surface of the bark. He planted these in peat soil, in one‑inch pots, and then plunged the pots into a moderate heat. A double cover of bell glasses was then placed over them, to exclude the air entirely, which course of treatment was pursued until they had taken root. The shortest time in which this could be accomplished was eight weeks, and the roots were formed in the following manner. First, a callus was formed at the base of the leaf, from which small fibres put forth; a small bud then appeared on the upper side (figure 16); a stalk then arose from this bud, which finally expanded into leaves and formed a perfect plant

An English writer remarks, that "the leaves or leaflets of a rose will often take root more freely than even cuttings, and in a much shorter time, but these uniformly refuse to make buds or grow."

This experiment is certainly very curious, and evinces how great, in the vegetable kingdom, are the powers of nature for the maintenance of existence, and is one of those singular results which should lead us to make farther experiments with various parts of plants, and teach us that in Horticulture there is yet a wide field for scientific research.

CybeRose note: The figure at right is from the 1883 edition.

When attempting to duplicate old experiments, it is important to get all the details right. It may well be that a mature leaf will root but never produce a bud. However, Lecoq specified that immature leaves were used. That could make the difference.

This is indeed an interesting experiment, but it might be more practical to take a leaf with some bark and the axial bud still attached. Eight weeks is a long time for a propagator to wait for a young plant to begin growth.

Lecoq's experiment was discussed in La rose: son histoire, sa culture, sa poésie pp. 248-249 (1844)
by Jean Loiseleur-Deslongchamps

Plusieurs végétaux, comme des expériences déjà anciennes nous l'ont appris, ayant la faculté de se multiplier par leurs feuilles faites de boutures, M. Lecoq a eu l'idée, il y a quelques années, d'essayer de propager ainsi les Rosiers. Il a cueilli de très-jeunes feuilles du Rosier de Bengale, à peu près au quart de leur développement, en les coupant au ras de leur aisselle ou de l'écorce, et il les a plantées en terre de bruyère, dans de très-petits godets n'ayant d'ouverture que la largeur du pouce.Ainsi préparées il les a enterrées, en les rapprochant trois par trois, dans une couche tiède ayant quinze degrés de chaleur. Puis il a recouvert d'un verre à bière chaque groupe de trois, et enfin pour que la privation d'air fût encore plus complète il a placé, par-dessus plusieurs groupes rapprochés, une cloche ordinaire à melon. Il a fallu sept à huit semaines à ces boutures pour s'enraciner, et ce n'a été que le plus petit nombre qui y soit parvenu. Dans l'intervalle M. Lecoq les visitait de temps en temps, en ne leur laissant prendre l'air que le moins possible. Quant à la reprise, voici comme elle eut lieu: il se forma d'abord un bourrelet à la base de la feuille, puis le bourrelet produisit des radicelles de sa partie inférieure, et il parut à la supérieure un petit bourgeon, d'où s'éleva enfin une tige qui développa des feuilles et une plante complète. Cette expérience est sans doute très-curieuse, car elle nous prouve combien sont grandes, dans le règne végétal, les forces de la nature pour la reproduction des êtres, et elle doit nous encourager à tenter de nouveaux essais de multiplication des plantes avec quelques autres de de leurs parties qui n'ont point encore été mises en usage, comme les folioles des calices, les pétales, les étamines, les pistils, etc.   Several plants, as already ancient experiences have taught us, have the ability to multiply by leaf cuttings, Mr. Lecoq had the idea, a few years ago, to try to propagate the Roses. He plucked very young leaves of the Bengal Rose, about a quarter of their growth, cutting them at the level of their armpit or bark, and planted them in heather, in very small cups having an opening only the width of the thumb. Thus prepared he buried them, bringing them three by three, in a warm layer having fifteen degrees of heat. Then he covered each group of three with a beer glass, and finally, so that the air-deprivation was even more complete, he placed, over several close groups, an ordinary melon-bell. It took seven to eight weeks for these cuttings to take root, and it was only a very small number that did. In the meantime M. Lecoq visited them from time to time, leaving them to take the air as little as possible. As for the recovery, here is how it took place: first a bead was formed at the base of the leaf, then the bead produced rootlets of its lower part, and on top a small bud, from where at last a stalk arose, which developed leaves and a complete plant. This experiment is undoubtedly very curious, for it proves to us how great are the forces of nature in the vegetable kingdom for the reproduction of beings, and it must encourage us to attempt new attempts at the multiplication of plants with some others of their parts which have not yet been put into use, like the leaflets of the calyxes, the petals, the stamens, the pistils, etc.