American Rose Annual 1977
Breeding With Hulthemia Persica (Rosa persica)
Jack Harkness
R. Harkness & Co. Ltd.
Hitchin, Herts., England

More than 140 years ago, a seedling of Hulthemia persica was raised in the Luxembourg Gardens in Paris. It was clearly a hybrid, having been pollinated naturally by a rose. It was introduced in 1836, is now known as Hulthemosa hardii, and to the best of my knowledge it has hitherto been the one and only hybrid of H. persica in existence. It is an attractive plant, though prone to mildew, and by its appearance I surmise its unknown pollen parent had a larger flower than H. persica, a longer flowering period, and bushy growth.

So unique and attractive is the colouring of H. persica amongst roses, that many breeders seized upon that one hybrid; but without success, for it proved sterile. Efforts to breed with H. persica itself were rarer, owing to the difficulty in persuading that plant to live and flower in cultivation, but such efforts as were made have left no mention of any success.

This report tells that Alec Cocker of Aberdeen determined to grow H. persica and to breed with it, reasoning that what happened once by accident could be made to happen again with intent. How, after obtaining seed from Iran, he generously shared it with me, in order to double the chances of success. How it fell to my good fortune, possibly due to the more suitable climate of Hitchin, to raise not one, but 50 separate hybrids during the nine years of work; and how we now propose to share these with other breeders, in order to hasten the day when roses of this most beautiful colouring may grow in the gardens of the world.

H. persica was for many years considered to be a rose, and still appears as Rosa persica in the R.H.S. Dictionary of Gardening. It is possible that it is a very primitive form of rose. Like the two species of the sub-genus Hesperhodos, it is a drought resisting plant, and has the prickly hips. It is interesting to note that R. stellata, which is probably its nearest relative, has 3 leaflets (sometimes 5), making a bridge between H. persica, with its simple leaf, and the less primitive rose species with five, seven or more. The course of the evolution of the rose is little known, and it may be that H. persica could teach us something of it.

Let us now study H. persica. It stands out from all wild roses by the chestnut red blotch at the base of each yellow petal. The flowers are small, about 4 cm in diameter; the petals are broad, with a cleft at the outer centre; but the base of the petals is so narrow, that they fall at a slight disturbance.

The red blotch is roughly in the shape of a fimbriated mushroom, the red and yellow colours intruding into each other at the edges. As the petals are usually 18 mm long, and the red blotch 7 mm, it will be seen that over one third of the petal length is red, albeit the narrowest third. The yellow colour is extremely vivid, and may prove to be the best source of yellow in roses, especially when one considers its unfading nature in view of its native habitat.

Marks on flowers very often serve as guides for insects; and no doubt the dark centre is for that purpose, especially in a yellow flower in semi-desert conditions of bright light. The supposition is strengthened by my belief that H. persica is a plant which prefers that its flowers are not pollinated by themselves, but rather by pollen from another flower; or indeed more likely from another plant. Why else do the stamens grow outwards, away from the stigmas, only curving back above them when their pollen is all but gone? I have noticed that fertile self-set seed of H. persica is very rarely produced in cultivation, and even though we do not emasculate its flowers, we have raised more hybrids than selfs in a ratio of 4 to 1. The existence of the red blotch argues that this is a flower that requires pollen to be brought to it by insects from elsewhere.

Filaments and anthers are yellow, and the stigmas are either pale, or slightly purplish; a colour variation I have not accounted for. The colouring of these organs has an important influence on the beauty of the hybrids. I have seen about a dozen flowers with no pistils, only a hole in the middle.

Twice we have had flowers of 6 petals, and of greater diameter than normal. In accounts of rose history, I have seen illustrations of the rose on the palace of Knossos in Crete. My six-petalled H. persica resembles that illustration more closely than any rose I know.

[Note: Rona Hurst, wife of C. C. Hurst, visited the site and found that the original fragments are of pink roses.]

The stems are thin, wiry, and have sharp, thin thorns. The leaves are simple, whereas all other roses have leaves of three or more leaflets. There are no stipules, contrary to all other roses.

The stems are bi-coloured, except when immature or very old. From each eye upwards there is a narrow strip of brown bark, and from each eye downward a strip of white.

The seed pods are round, and wickedly bristly; or rarely they are flat, like a disk. They ripen early, and need to be harvested a month before our normal harvest time, otherwise many fall off.

The seed germinates easily; and very rapidly the seedling grows a long tap root, so that a 3 inch seedling may have a root 18 inches long. The seedlings are succulent to the touch, and are exceedingly prone to mildew, by which they can easily be lost. They are light greyish green, the leaves very close together.

Our plants of H. persica, however, once grown past the seedling stage, have been extremely healthy; as also have been the hybrids. I cannot recollect seeing mildew, blackspot or rust on any of them. We have grown H. persica out of doors over winter; it stood the frosts of two winters without damage, but eventually died, I suppose from a dislike of excess moisture.

H. persica, according to repute, cannot be propagated by cuttings or budding. I have not tried. But it will produce runners, which on three occasions in our greenhouse have travelled under concrete paths, to surface some 6 feet away.

It is somewhat sparse in flower, and we usually find that the flowering is confined to a few of our plants. We have kept a flower count over the years, and can illustrate thereby what an awkward customer we are dealing with. The seed was sown in February 1967 and some more in February 1968. We should perhaps allow for 10% more flowers, which we may have missed counting:

Year No. of Plants No. of Flowers
1968100 19
1969140 32
1970140 26
1971140 289
197218 77
197318 78
197418 206
197518 280
197618 329

The plants are grown in an unheated greenhouse, where they begin to flower after mid-April, and finish in early June.

It is now time to turn to the story of our breeding. For much of the last nine years, we have used the pollen of H. persica without any success at all. It is possible that a determined effort with diploid parents might succeed, but if so I have no evidence to offer by way of encouragement. We had a whole bench of diploids for this purpose one year, and I have even raised my own diploid parents to try and make a mate for H. persica's pollen.

Therefore we now tend to concentrate on seed, which has the advantage that if one sows a seed from a plant of H. persica, a hybrid is identifiable in the seedling stage as soon as it shows a compound leaf.

The first two years, we got nothing to germinate, despite the use of giberellic acid, which accordingly we discontinued. It occurred to me that seed set might be better if there was reproductive activity from natural fertilisation. Therefore we ceased to emasculate the flowers, except to the extent we required pollen; after all, that was how Hulthemosa hardii was born, and I had no objecion to growing some self-set H. persica seedlings. But strange to say, out of 2,000 seeds harvested, only 12 "selfs" have appeared.

The policy of leaving the stamens on had an immediate reward, whether deserved or not I cannot say. In 1970, we had 33 hybrids germinate, of which 27 were H. persica x Canary Bird and 6 were H. persica x Ballerina.

All the Canary Bird crosses survived, providing a most interesting range of variations in this cross. All had 5 petals, all had shrubby growth from 3-6 ft. tall, all flowered in May, and all had leaves and stems showing Canary Bird influence. We observed interesting variations in the red centres and in flower sizes.

Every one had a flower larger than H. persica, which averages 4 cm in diameter. The smallest was 5 cm and the largest 7.5 cm, the overall average flower diameter of the 27 hybrids being 6.5 cm. The flowers are borne singly on short stems arising from leaf axils; occasionally terminally. These axillary flower shoots are longer than those of Canary Bird.

The red blotch of H. persica extends usually 7 mm from the petal base; despite their larger flowers, the red blotch of the hybrids was in no case greater than 7 mm, and in only two cases did it in fact equal 7 mm. In some it was only 3 mm, and sometimes virtually un-noticeable until a petal was plucked, through being hidden by the stamens. The red blotch was consistently deep in colour, but in some hybrids became lighter with age. I notice it is sometimes absent on the first few flowers that open.

The stamens were normally red and yellow, the anthers of some being yellow edged with red. A few hybrids had pure yellow stamens.

The stigmas were mostly pale, but in one case coral, and in a few cases pure yellow. Where the yellow stigmas coincided with yellow stamens, the floral effect was extremely beautiful, despite the red blotch of those hybrids being small.

The leaves were extremely interesting. There were variations of size and density between the hybrids, but they all had compound leaves of 7 or 9 leaflets, or occasionally 5 to 11. The terminal leaf was in most cases strange, being irregular, as though partly cleft into two or three. Sometimes the main vein can be seen to branch towards the imperfectly cleft parts of the terminal leaf. Rudimentary leaves are common where lateral growths arise.

All the hybrids had stipules, but these were irregular, as though undecided whether to grow into stipules or leaflets. On some growths, the stipules joined to the bottom pair of leaflets; in others, there is a small leaflet below the bottom pair of leaflets. The common form of stipules is narrow at the base, and extending from the leaf stalk like small wings.

The hybrids were less thorny than we expected, indeed less so than the average rose. The seed pods were smooth, the bark was handsome, usually with brownish red colouring. Most hybrids had a pleasant scent, all were April-May flowering, varying from 3 to 4 weeks (under glass), and all had a glorious yellow colour. Their appearance was handsome, their growth free, except for one or two weak ones.

Of the six hybrids from H. persica x Ballerina, we succeeded in raising only one. This has a flower of 3-4 cm diameter, smaller than H. persica. The red blotch is very dark and prominent, and measures 6 mm, over one third of the petal length. In this hybrid, the petals are persistent, whereas in all the previous ones they fall easily. In fact they stay on this plant until they have turned from yellow to greyish white, and until the red blotch turns magenta. The reverse of the petals is greenish yellow before fading.

This hybrid produces flowers in clusters (also singly), mainly on side shoots, but also terminally on main shoots. It has leaves of 3 or 5 leaflets; the leaves are narrow, evenly serrated, less graceful than those of the Canary Bird hybrids. The stipules have leafy growth, also serrated. Growth is short and bushy, scent very little, and the flowering period is about 6 weeks.

We obtained over 800 seeds from H. persica crosses in the following three years, of which six hybrids germinated, and only one was successfully raised. We had been tempted to use Scotch roses, because of their remarkably fertile pollen; but the resultant seedlings failed to survive, after germinating in November. Two seedlings of H. persica x R. rugosa alba also failed. Probably no two diploid species of roses are more dissimilar than H. persica and R. rugosa; at all events the seedlings from that cross try to make leaves from the seedling stem at intervals of 3 or 4 mms, and their effort exhausts them before they are very high. We also lost another seedling of H. persica x Ballerina.

However we raised an interesting hybrid, H. persica x Buff Beauty. This proved to be quite different from any we had previously, for it had 39 petals, was light yellow, with paler reverse. The yellow was deeper in the centre of the flower, and the red blotch was narrow, shaped like a spinning top, so narrow at the base that part of the petal base was yellow. The flower diameter was 3.7 cm, the stamens were petalloid. The flowers appeared terminally, one per shoot, and on maiden budded trees. Leaves were small, usually of 5 leaflets, of which the terminal one is the largest. The stipules were small, and the growth low and spindly.

In 1975 we obtained 8 hybrids all of which germinated in November. We carried them safely over winter, but then the four from R. rugosa alba behaved as previously; we were left with three H. persica x Phyllis Bide and one H. persica x Cornelia.

The Phyllis Bide crosses have flowered, and two of the seedling plants are extremely vigorous, if somewhat straggly, having a spread of some four feet each, 18 months from germination. One is single, with a well marked red blotch. Its flower is yellow, not as vivid as H. persica and it persists until the colours, both yellow and red, lose their brightness. The diameter of the flower is 6 cm and the red blotch measures 6 mm from the petal base. The shoots are thin, the leaves small, with 3 or 5 leaflets.

The second Phyllis Bide hybrid has 35 petals. It is the first of our hybrids to show a colour change, for the colour is not pure yellow, but orange yellow. The red blotch is present, although not prominent, owing to the flower formation hiding it. The flower has a diameter of 5 cm.

The third Phyllis Bide hybrid is not very strong, and has borne one flower. This has 65 petals, light yellow, with a red blotch.

The H. persica x Cornelia seedling has not yet flowered.

This year is the most interesting of all because 27 hybrids germinated, of which we have lost seven; however we still have some of each cross, namely, 3 H. persica x Trier; 1 x R. chinensis mutabilis; 6 x Phyllis Bide; 6 x Cornelia; 1 x Margo Koster; 2 x Mermaid and best of all, we hope, a second generation in H. persica x (H. persica x Canary Bird). None of these have flowered.

A summary of the work involved in the 8 years' crosses:

Pollination
Year
Crosses Pods Seeds Hybrids
Germinated
Hybrids
Raised
1968 19 15 3 - -
1969 32 6 24 - -
1970 26 26 76 33 28
1971 289 269 444 5 -
1972 77 36 160 1 1
1973 78 26 213 - -
1974 206 188 852 8 4
1975 280 270 358 27 20
TOTAL 1007 836 2130 74 53

The aim is to breed garden roses with the beauty which H. persica offers. And the tool we need is a fertile hybrid. We cannot yet guarantee that we have one, for although our Canary Bird hybrids produce seed on rare occasions, we have failed to germinate it. I hold to the belief that out of so many hybrids, if sufficient breeders try them, and particularly in different climates, someone somewhere will succeed. We ourselves have one second generation seedling from our hybrid pollen. Therefore I have determined to part with my research material to any plant breeder or research institute in the world who is interested, either for breeding, or for other research, or to hold stock of plants which are of some botanical and horticultural interest. I should add that we are asking a reasonable price for thus supplying our rivals with ten years of our work; and it is my intention, when I have looked for the most hopeful breeders among the recent hybrids, to make them also available to our subscribers, so that in case they are unsuccessful with the present batch, they will know that my research material will be available until someone has made the break through we all wait for.