Gardeners' Chronicle, August 2, 1924
Rosa banksiae hybrid 'Di Castello'
Dr. Attilio Ragionieri
Castello, near Florence, Italy
In the Gardeners' Chronicle, January 5, 1878, page 22, was published a note by Dr. Fenzi of Florence, concerning three single-flowered (two white, one yellow) varieties of Rosa banksiae, raised in 1868 by the late Paolo Baroni, curator of the Botanic Garden dei Simplici, Florence, from seeds harvested from a double-flowered variety of this species. Dr. Fenzi's note indicates that these varieties were bearing every year a certain quantity of fertile seeds.
Some twelve years ago through the kindness of the late Professor Baccarini, directory of the Botanic Garden, I received two plants of these single varieties, one white, the other yellow coloured, and I planted them in my garden side by side. They are now covering a wall some metres high, facing east, and bear every year early in April a profusion of pretty, single, sweet-scented flowers, that are unfortunately ephemeral. But, strange to say, I have not been able to gather a fruit from those plants except after cross-fertilisation, which is strongly contrasted with the fertility noted above in the Botanic Garden of Florence.
For eight years I have made many attempts to cross-fertilise these single varieties, and I find that obtaining fertile seeds by this means is not an easy matter. Owing to the autosterility of both those varieties and the absence of any other species or variety of Roses blooming in my garden at the same time; the work of hybridation is very simple and consists only in the pollenisation of the stigmas without any preparation of the flower. As a consequence of the earliness of flowering it is a little difficult to procure pollen of other species and varieties, except from forced plants. For my experiments I have been able to make use of the pollen of the following species and varieties:Rosa gigantea, R. bengalensis fl. roseo pleno, Fortune's Yellow, Lamarque, Candeur Lyonais (HP), Climbing Caroline Testout (HT), Safrano (T), Maréchal Niel (T), Climbing Frau Karl Druschki (HP), Etoile de France (HT), Ulrich Brunner (HP), and a few others.
Cross-fertilised flowers rarely bear fruits and, more rarely, fertile seeds. The fruits are like a small Pea and when they contain a single round seed some promise of germination is offered, but when two or three small, irregular seeds are produced, they are certainly sterile. To give an idea of this difficulty I may state that from a quantity of seeds collected from fifty fruits last year and sown with every care in November in a greenhouse, only one plant has been produced; and I have only six plants representing the work of eight years. These are the results from the following crosses:
The parentage of the two remaining plants is not recorded. The crosses between R. Banksiae alba and lutea simplex and R. gigantea bore fruits, but the seeds did not germinate. I have given the name of Rosa Banksiae hyb. Di Castello to the only hybrid I have flowered, and this plant is the result of crossing of the simple R. Banksiae lutea with Lamarque. This hybrid has a robust constitution but is less vigorous than the mother, though more hardy. The branches, almost spineless, bear an abundance of double flowers of the purest white, about seven centimetres in diameter, sometimes singly, sometimes in clusters of three; they flower successively, are very fragrant and last some days in perfection.
The time of flowering is early in April at Castello.