HORTICULTURE 2(20): 495-496 (November 11, 1905)
Rose Hybridization
John Cook

In my researches in plant physiology I find the credit of discovering the sexes of flowers belongs to a Frenchman. The botanist who wrote after the Renaissance hazarded some vague conjectures on this subject, and it was only towards the end of the 17th century that the true functions were assigned with precision, to the pistil and the stamen. Tournefort rejected the fact of fertilization, and persisted in considering the stamens as organs of excretion. After his death, the most devoted of his disciples, Sebastian Vaillant, in a discourse, delivered in 1716 at the King's garden, explained the functions of the stamen, and demonstrated, incontrovertibly, the phenomena of fertilization of plants. Eight years later Linnaeus (Linne) popularized the doctrine of fertilization by his writings, which were no less remarkable for their logical accuracy and poetic charm.

As to the rose, I will only write about the visible organs, namely the stamen and the pistil. What we, as florists, consider a perfect rose, is in a botanical sense an imperfect one, as the stamens have mostly grown out into petals. The pistils which arise from the center are the organs through which the pollen is carried to the ovule; the stamens surround the pistils, and produce the pollen in little sacks at the extreme end.

Having selected the flower you wish to work upon remove all the stamens before they show any pollen. Then select the flower you wish to be the pollen bearer; if the pollen has not already appeared on it, cut the flower, remove the petals and put the stem in a cup of water until the pollen appears. When the nectar or watery substance appears on top of the pistil is the time to shake the pollen on a white saucer, pick the same up with a camel-hair brush, and carry it to the top of the pistil. As the pollen sometimes is very scarce, it is better to put it only on two, or three pistils, repeating the operation the following day.

It takes a great deal of pollen to make one seed. The pollen grains are living cells, and with these cells, life begins. Why does the seed fail to come up sometimes? Because the flower has been insufficiently pollenized or the pistils were imperfect. A great many of them I have found twisted and crooked, which prevents the pollen from being carried down through the pistil. This I've found the case in the most of our florist roses, such as the Bride, Bridesmaid, and American Beauty. The shell, or the covering of the seed which adheres to the side of the hilum, is fed from the stem below, and is not dependent on the pollen. We find plenty of what the florists call blind seed, namely, the covering without a germ, which proves that no pollen has ever entered it. It takes from four to six months to ripen the seed. When the stem of the hip begins to get yellow then the seed is ripe, take it off, wash the bulb and put it in a pot in sand, which is to be kept wet, and in a short time it will be rotten, when the seed can be washed out, and sown at once, before it gets dry. If the shell gets dry, it gets harder and consequently it takes longer for the seed to germinate, which takes usually from three to ten months. The enemies of the seedlings are snails and other insects and mildew.

There are over five thousand varieties of roses in cultivation. Like many other plants, the rose has a tendency to revert to the original single form, which prevents us to get quickly the desired results from our hybridizing. I started with Bon Silene and Caserta, as seed bearer, and hybrids as pollen bearers. I soon found that the pollen bearer had too much influence, as the most of the seedlings went back to the habit of hybrids. One of the best as a seed bearer to reproduce its own habit in growth and production of flowers is Maria Van Houtte. It partakes freely of the color of the pollen bearer, but the flowers of the progeny are mostly only semi-double. If I were to give all my experience with the great number of varieties I worked on it would occupy too much space in your valuable paper. The best results have come from recrossing my own seedling. My work has been mostly under glass. There will be plenty to do for centuries to come in the field of hybridizing.

Cook: Rose Breeding (1906)

Cook: Rose Breeding (1907)

Cook: Rose Breeding (1915)