What's up with Rosa foetida?

I have long wondered how a species that is nearly sterile could survive in the wild. I once read that Rosa foetida bicolor has only about 5% viable pollen. Lutea and 'Persian Yellow' are apparently about the same. Perhaps the near-sterility is "environmental", as in the cases cited by Nicholas (1927):

"Have the soil and original method of propagation a direct relation to the fertility or sterility of a plant? We have long noted here that grafted plants of R. Hugonis, for example, will profusely bear seeds, while plants grown from cuttings are very scant seed bearers, almost approaching sterility. Paul's Scarlet Climber as an own root plant may be considered as sterile, but a grafted plant will bear both self- and hand-pollinated seeds. I have also noted that plants of the same variety in different parts of the nursery have a different seed bearing capacity, although both receive the same amount of sunshine. As an instance, R. bracteata and R. Altaica at one location are practically sterile, while a short distance away, but in a different soil, nearly every bloom, either hand- or self-pollinated, sets fruit."

Darwin ('Double flowers—their origin', Gardeners' Chronicle, no. 36, 9 September 1843, p. 628) also recognized the influence of environment on fertility:

"It is well known that plants (and indeed animals, as I could show by a series of facts) when placed out of their natural conditions, become, often from apparently slight and unintelligible causes, sterile. How many American plants fail in producing pollen in this country! the anthers of the Persian and Chinese Lilacs, as I observed this summer, are as destitute of good pollen as if they had been hybrids. Other plants produce good pollen, but are defective, as it appears, in their ovules, as their germen never swells. Linnaeus has remarked that most Alpine plants, when cultivated in the lowlands, are rendered quite sterile. In most of these cases, we see that sterility is compatable with long life and health."

Maybe it's a matter of climate. Floral induction (conversion of vegetative buds to floral buds) may be triggered by different conditions in related species. And floral induction may precede flowering by months. In the strawberry, Fragaria vesca, floral induction occurs during the short days of autumn, but both the floral and vegetative buds remain dormant until the following spring. A long autumn (late first frost) means more flowers will open the following spring. An early frost, on the other hand, means fewer flowers.

When does floral induction occur in Rosa foetida?

Floral induction often occurs while plants are dormant. Not always, of course, as Fragaria vesca shows. But it may. Rosa foetida seems to be adapted to a short growing season in region where summers are fierce. It emerges early from dormancy, flowers, ripens its fruit (presumably) then sheds its leaves before the onset of scorching summer heat.

Nicolas: The Rose Manual p. 265 (1933)

"Summer defoliation is not always due to disease, although diseases will precipitate it. Summer defoliation did not bother our fathers before the introduction of Austrian Briar blood. Austrian Briars will lose their foliage early because it matures early. It is the nature of the beast that nothing can change, and all their hybrids inherit that character in a greater or lesser degree. When the foliage is mature, the ‘cortex’ or film of corky material that heals the pores where the leaf is attached to the branch begins to form, the leaf receives less and less nutrition from the plant and drops at the least provocation, spray or dust notwithstanding."

Would Rosa foetida be more fertile if the plants were grown own-root and allowed to go dormant in summer rather than kept growing by alien root-stocks? I don't know. But perhaps someone who grows the species, and who has a magnifying glass and an X-acto knife, would be so kind as to sacrifice some axial buds to determine just when the vegetative buds are transformed into flower buds.

If floral induction in the species does occur in summer, this may help explain why some of its F1 hybrids (e.g. 'Soleil d'Or') are able to rebloom, since it would only be necessary to override the summer dormancy.

There have been reports of the single yellow rose bearing viable seeds. Gerarde (1596) disagreed with the notion that the yellow rose was merely a wild rose that had been grafted onto a broom plant. He commented that, "the seeds of yellow Roses have brought forth yellow Roses, such as the flours was from whence they were taken". D. Don, in The British Flower Garden (1835) wrote of 'Williams's Double Yellow':

"This interesting variety was raised about ten years ago by Mr. John Williams of Pitmaston, near Worcester, from seeds obtained from the single yellow rose, which but very rarely matures its fruit in this country. Among the seedlings raised on that occasion three proved to be double, one of which is the subject before us, which from its flowering freely, and from the size, form, and colour of its blossoms is justly esteemed a most valuable addition to our collection of hardy roses."

Rivers (1836) reported similarly, that the Single Yellow Austrian Rose, "in a state of nature, seldom if ever bears seed, yet, as I have proved, it will, if its flowers are fertilised."

The native home of Rosa foetida has been discussed repeatedly since its introduction. Dr. Masters, in the Gardeners' Chronicle (July 7, 1906), wrote:

"Not long since a correspondent enquired about a yellow-flowered Rose occurring in Syria, where the profusion and beauty of the flowers were very noteworthy, as noted also on the slopes of Lebanon by Sir John Llewelyn. From the description given, we conjectured that the plant was the Rosa lutea of Miller, of the Botanical Magazine (tab. 363), and of Lindley's Monograph of Roses (1820, p. 84). This conjecture was verified by the inspection of Syrian specimens obtained subsequently by Mr. Arthur Sutton. This plant was called by Linnaeus Rosa Eglanteria, a name adopted in the Index Kewensis, which is unfortunate for many reasons, which we need not discuss here. When the Syrian flowers just mentioned were subsequently submitted to Col. Prain, the Director of the Royal Gardens at Kew, he at once recognised them as those of an Indian Rose—R. Eglanteria of Linnaeus, which is, as we have said, synonymous with R. lutea of Miller. It is described in Sir Joseph Hooker's Flora of British India (II., 1897, p. 360), and stated to be a native of the drier parts of the Himilayas from Kistwar westward, and in Western Tibet. Afghanistan, Asia Minor, and Siberia are also mentioned as countries wherein this Rose is found native."

This was also reported in the J. Roy. Hort. Soc. (1907) and a follow-up report came the following year.:

"Yellow Rose from Palestine.—Mr. A. W. Sutton, V.M.H., read a letter from a correspondent concerning a yellow rose which grew near Baalbec, specimens of which he also showed. Dr. Masters recognised the rose as Rosa lutea, and Sir John Llewellyn said he had seen it growing so profusely on the northern slopes of Mount Lebanon as to make a mass of colour visible at the distance of a mile."

The Gardeners' Chronicle p. 408 (1908)
Rosa lutea.—In June, 1906, Mr. A. W. SUTTON, F.L.S., showed before the Committee dried specimens of a yellow Rose which had been named at Kew Rosa Eglanteria (= R. lutea) from Baalbec. Mr. SUTTON subsequently obtained through a lady missionary at Baalbec some pods and shoots of this Rose, but they were dead when they arrived. Later, however, he received other seeds, from which three plants had been reared, and which were now flowering in his garden. He exhibited a flower of a beautiful clear yellow colour, measuring 3 inches in diameter. A full account of the history of this plant, which Colonel PRAIN thought when he saw the dried specimens from Baalbec to be identical with the Indian Rose Eglanteria, is given in the Gardeners' Chronicle, July, 1906.

The fragrance of the leaves of R. foetida is commonly overlooked. The precise fragrance has been disputed.

Herball p. 1086 (1597)
John Gerard
The yellow Rose hathe browne and prickly stalks or shootes, five or six cubites high, garnished with many leaves, like unto the Muske Rose, of an excellent sweet smell, and more pleasant than the leaves of the Eglantine.

Rhodologia: A discourse on roses, and the odour of rose (1844)
John Charles Sawer
The leaves of R. lutea, Dalech (R. Eglanteria, Lin.), (known also as R. Capucine) possess an odour which is even finer, recalling that of jasmin.

Euphytica 27: 205-210 (1978)
On the transmission of the yellow flower colour from Rosa foetida to recurrent flowering Hybrid Tea roses
D. P. De Vries and Lidwien A. M. Dubois
The F1 seedlings were relatively uniform as to vigour, showing a decidedly R. foetida habit. Thus leaves were composed of 7-11 leaflets (3-5 in HT) which had, like R. foetida, the typical smell of sour apples.

E. H. Wilson (1915) included R. foetida among the yellow roses native to "Asia Minor and Persia to central Asia," then added that it was also to be found in the Crimea.

A species with such a wide range will surely have a variety of geographical races or localized populations that differ in various characteristics. Maybe a dwarf form is out there, or some that keep their leaves for a longer season. Are there other variations of the Bicolor type? At the very least, it would seem worth the trouble to import more forms of the species so breeders won't be forced to continue exploiting the limited "gene pool" of the clone that has come down to us.

The mystery deepens!

I have been exchanging emails with Peter Harris, who has been collecting all the info he can find on 'Harison's Yellow' and the numerous imposters that travel under that name. There are quite a few. Many are probably OP seedlings of 'Harison's Yellow'. But 'Williams' Double Yellow' and 'Williams' Superb Yellow' were originals from England that reached the U.S. early and no doubt were mistaken for HY. Then there were 'Feast's Seedling' and Hogg's several yellows, all presumably seedlings from 'Harison's Yellow'.

'Allard' is probably the seedling raised by Prof. Allard (1900) from seeds of HY. Doorenbos crossed it with an unspecified spinosissima, and in the F2 raised 'Ormiston Roy', grandparent of 'Golden Wings'.

The big surprise in all this is that most of the various specimens called 'Harison's Yellow' collected so far are triploid. So is 'Persian Yellow', 'Hazeldean' (R. altaica x either 'Persian Yellow' or 'Harison's Yellow') and all the seedlings of 'Hazeldean' that Peter has found.

What's going on?

Something suspiciously similar happens in the genus Rubus. A diploid blackberry crossed with a diploid raspberry produced only triploids and tetraploids. Not a diploid hybrid in the bunch. Darlington (1949) wrote, "We have to visualise a single super-gene consisting of many parts with mutually adjusted effects."

In other words, it may be that such a "super-gene" exists on one or more chromosomes of Rosa foetida that creates a physiological disturbance in hybrids with most other species. The only way for an embryo to be fully viable is for the "super-gene" to be excluded. And then the other chromosomes are excluded as well to maintain other necessary balances.

One notable exception is 'Lady Penzance' (R. rubiginosa x R. foetida bicolor). An irregular pentaploid (4+1) pollinated by a regular tetraploid (2+2) should give a hexaploid offspring, which is just what happened. Apparently all those unpaired chromosomes dilute or override the influence of this (hypothetical) foetida super-gene. Then there are the two once-blooming offspring from the HT 'Souv. de Mme Eugene Verdier' x 'Persian Yellow'; 'Lawrence Johnston' and 'Le Rêve'.

That's the best I can come up with at the moment.

Has anyone tried crossing spinosissima and foetida?