Trans. Iowa State Horticultural Society 86: 201-202 (1951)
ROSA LAXA’S ROLE IN ROSE BREEDING*
*Iowa Rose Reporter—January, 1951
F. L. Skinner, Dropmore, Manitoba
One of the biggest problems that faces the breeder of hardy roses for the Great Plains area is the fact that a large percentage of hybrids between garden roses and the hardy species have proved more or less sterile, and as the wild species is usually the dominant parent very few of the first hybrids come up to their raiser's ideal of a garden rose.
When, therefore, one comes across a wild species that will inter-breed with a wide range of garden roses and give a fair percentage of hardy garden rose types, I feel that it is a matter of considerable importance to the breeder of hardy garden roses.
From the work I have already done with the true Rosa laxa, I believe I have found just such a species; the first hybrids of Rosa laxa raised at Dropmore, though they produced seed freely if left alone, refused to set seed to the pollen of the garden roses which I used on them. However, their pollen was effective on some other roses on which I used it, and some of the resulting seedlings flowered during the past summer. Five of these were selected for further experimental work; one fully double, three semi-double and one single, all flowering throughout the most of the summer. Pollen of a wide range of garden roses was used on them; the fully double form set no seed at all; two of the semi-double forms set seed on some of the flowers that had not been emasculated, and the remaining semi-double and the single form set seed to practically the whole range of pollen I used on them. The pollen used came from a wide range of roses, including Patricia Macoun, (a seedling of Rosa Helenae), a dwarf white polyantha, and an unnamed very double white rugosa hybrid. Seed was also set to the pollen of a variety of Rosa alba that I secured from Scotland as the result of my visit there in 1947. The previous winter had been a severe one in Britain and in the north of Scotland, most of the Hybrid Teas had been cut to the ground while this form of Rosa alba was alive to the tips and growing to a height of six feet. It is of much more slender growth than such other varieties of Rosa alba as Maiden’s Blush or Celestial and by bending the branches down so that they were covered with snow all winter, they have survived the past two winters without injury. The flowers are pure white, fully double, very fragrant, and unlike Maiden’s Blush, it sets seed quite freely.
I also got seed to set on these laxa hybrids from the pollen of a hybrid of my own which was flowering for the first time. This had a Hybrid Perpetual as a seed parent with a hybrid of Rosa acicularis and R. hispida as a pollen parent. Its flowers were fully double, of very good form, and the white buds opened to a very pale blush pink. It continued to bloom from early July until October. Rosa hispida, by the way is closely related to R. altaica, but the stems are clad with fine prickles instead of thorns.
Unfortunately, the unexpected August frosts caught most of my hybrid rose seeds in an immature state, and I am afraid few of them were ripe enough to germinate; the fact remains however, that these hybrids of Rosa laxa set seed to the pollen of a wide range of garden roses in 1950, and will most likely do so again.
(Mr. Skinner sent a snapshot of the HP x R. acicularis x R. hispida seedling. It shows a very well-formed bloom with dainty foliage. GJB.)