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From the book, Redoute Roses (Les Roses), "Rosa banksiae ('Lady Bank's Rose') Description... Flowers small, with a sweet penetrating scent like violets... petals 4-5-seriate, pure clear white, those at the centre curled and crumpled... This rose was imported from China in 1807 to England and is dedicated to Lady Banks, wife of the Illustrious Banks who was one of the scientists on Captain Cook's expedition."
Once blooming, pricklefree, totally evergreen in temperate climates and possessing elongated foliage, Banksia is available in single and double white and yellow forms. It is now quite common throughout warmer regions of the world. Individual specimens can grow to be enormous size given the right weather and soil conditions. The commonly found garden forms are thought to be ancient Chinese selections of the species.
The Guinness' Book of World Record lists a Double White Lady Banks, (Rosa banksia banksia), growing in Tombstone, Arizona as the worlds largest rosebush. It covers over 8,000 square feet and has a trunk approximately 12 feet in circumference.
Anyone working with hybridizing Rosa banksia knows it's one of the more difficult species one can attempt to work with. Not only is it tender and blooms earlier than most species, but it rarely accepts pollen of any type, including its own. As species banksias have much to offer those breeding roses for temperate climates.
Documented use of banksia in hybridizing was originally accomplished by Dr. Attilio Ragionieri in Italy as he noted forms he had received there occasionally set open pollinated hips and so offered an opportunity for hybridization. His efforts were detailed in an article published, Gardeners' Chronicle, August 2, 1924, entitled, Rosa banksiae hybrid 'Di Castello'.
'Di Castello', still in commerce, is a cross of R. banksia lutea x Lamarque. It's interesting to note here that Ragionieri utilized the double yellow form of banksia. First of all, there are those that theorize that banksia lutea might be an ancient garden hybrid in its own right because of the yellow color. Secondly, double forms of species are more often less fertile than single flowered forms. Those attempting to utilize this hybrid in breeding would hope for fertility as both parents being diploid should theoretically produce fertile offspring. This has not proven to be the case. No hybrids using this cultivar have been recorded.
Banksia was next taken up by Quinto Mansuino, of San Remo, Italy, detailed in the American Rose Annual 45:15-18 (1960), entitled, Breeding Miniatures in San Remo.
Many fertile crosses were accomplished, as he states,
"I had more interesting results from the cross R. chinensis minima (Tom Thumb var.) x R. banksiae lutescens and its reciprocal. The series of hybrids obtained varies from the dwarf ones of about eight inches to the big climbing ones; some thornless, all having good ornamental foliage. The blooms are white, in corymb, long lasting and very decorative."
At this time Mansuino was in contact with American rose hybridizer Ralph Moore. Conversations with Moore indicate that while Mansuino's hybrids were fertile, propagation was problematic. Apparently these hybrids did not strike easily from cuttings and were not easily budded. This might have only added to their lack of popularity.
I suspect they were not considered unique enough by the public to warrant wider distribution despite their unusual parentage. Photos indicate these hybrids were attractive but emphasis at the time these hybrids were created was on large flowered hybrid teas. Mansuino did create a very popular florist's rose, 'Bride's White', 1968.
It's been theorized by Kim Rupert that banksia might well lie in its undocumented ancestry.
Attempts to revive interest in Mansuino's work have begun in the U.S. by importation of some lesser known hybrids still preserved at the Fineschi Gardens in Italy. It is my hope that these creations will be taken up again by collectors and hybridizers. I personally recently received one these hybrids, 'Letizia Bianca', for which documentation seems to have been lost. As open pollinated hips form on this variety I have hopes to utilize it in the future. Mansuino is best known for a sterile hybrid, 'The Pearl', Tom Thumb (Miniature, deVink, 1936) x R. banksiae lutescens. Note use of the double yellow form of banksia, as pollen parent.
My interest in Rosa banksia goes back to the 1980's when I was a young horticulture student. Conversations with Ralph Moore at the time led him to experiment for a time with use of banksia. Later conversations revealed that he abandoned working with banksia due to lack of progress. Having learned that a hybridizer of Moore's stature abandoned attempts, I largely gave up hopes of working with banksia on my own.
I was doing very little hybridizing but continued to work in the horticulture industry and began to collect roses, primarily rare and old garden varieties.
It was at this time in the year 2000 I was contacted by a hobbyist rose hybridizer, A.C. Tunningley in upstate NY in regard to a source for 'Grey Pearl', a variety he had been seeking for several years. I advised him that I had it and he could get a specimen from Ralph Moore's Sequoia Nursery.
This began a dialogue regarding roses and rose hybridizing that still continues. In one of our many conversations I was surprised to learn that he had done experiments with crosses of Rosa banksia banksia x 'Old Blush' which had resulted in a handful of seedlings most of which were sickly and eventually discarded. He had preserved one unusually vigorous seedling that was now taking up most of his 40' greenhouse space. His pet name for his creation was, "The Monster". Note banksia used here was of the same type listed as the "World's Largest Rose Bush".
This hybrid was a very vigorous once and shy blooming double cerise rambler. Out of appreciation for my advice regarding 'Grey Pearl', he offered to send me pollen although he had very little to share due to the double nature of the blossoms. Though he had largely abandoned attempts at use of the pollen himself due to lack of success. I agreed to give it a try though I was a bit incredulous.
This original banksia hybrid is now lost and recent attempts to recreate something similar have not met so far with success. Tunningley theorizes that conditions must be exacting in order to use banksia successfully as seed parent and those particular conditions are difficult to replicate. I have personally never observed mature seed baring hips on Rosa banksia in California though I suspect some coastal climates might offer conditions favorable to hip formation. Fred Boutin in Tuolumne, CA has experienced hip set on a heavily prickled mature R. banksia specimen derived from seed collected in the wild.
Unfortunately weather conditions in the Palm Springs area where I garden had already turned warm by the time I received pollen from "The Monster" via pollen transferred to a Q-tip . I now know higher temperatures sometimes aid in the creation of disparate hybrids though they can reduce overall fertility. I knew from my years of collecting and experimentation in the area that there was only likely one variety that would accept pollen under these conditions. Fortunately the californica hybrid 'Lilac Charm', though a tetraploid, was in flower at the time. I dutifully emasculated the blossoms and applied the pollen the next morning. There were only four blossoms at a stage for emasculation. So it was that these four were utilized and labeled. Hips formed and were allowed to mature and seed were sown un-chilled in September. From about 20 seed only one seedling emerged. I assumed this one seedling to be undoubtedly the result of pollen I missed during emasculation so I largely ignored it. I did note that the seedling looked odd and seemed to be having trouble developing as the leaves were distorted and slow to develop. It didn't progress through much of the warm weather that season. When it did flower, an unimpressive mauve single appeared. I pretty much ignored it further as it seemed hybridization was highly unlikely. I preserved the seedling only out of interest in its odd behavior.
As the weather began to cool that year, we began to experience a flush of growth as is normal for us. It was at this time that while studying my seedlings one morning I came to the realization that this seedling was indeed a new banksia hybrid. The cooler temperatures had initiated a flush of growth that bore an unmistakable resemblance to the elongated leaflets of Rosa banksia.
So it was that the cross , 'Lilac Charm' X (Rosa banksias banksia x 'Old Blush') was eventually given the study name 'Lila Banks' and registered as such with the ARS.
Some five years later I can now attest to the fact that 'Lila Banks' is one of those horticultural anomalies that occasionally present themselves, a fertile triploid. Not only is it a fertile triploid but a repeat blooming shrub to about 3' tall and wide, a size derived from both 'Old Blush' and 'Lilac Charm'. Hardly the offspring one would expect from "The World's Largest Rose". This cross could just as easily have created a giant sterile triploid rambler. In contrast to the hybrids created by Mansuino, this variety strikes easily from cuttings.
Early attempts at using 'Lila Banks' pollen resulted in many hips but seedlings were lost to various misfortunes so fertility could not be proven until 2004.
In reading about Mansuino's attempts I noted that he makes mention use of 'Ophelia', as he states, "I have the best results regarding the flower shape and the cut qualities using the true Teas and Hybrid Teas of the Ophelia offspring."
I do not grow 'Ophelia', but I do grow and had grown seedlings of this rose's purported parent, 'Antoine Rivoire'. So it was that the cross 'Antoine Rivoire' X 'Lila Banks' was made and of the resulting seedlings one unmistakable hybrid was selected and given the name, 'Riverbanks', in 2005. This variety also strikes easily from cuttings.
Of interest in 2005, the first open pollinated seedlings of 'Lila Banks' were germinated. I had assumed from earlier attempts that this variety was seed sterile. Though hips do form on occasion, they seem to appear only sporadically under cooler conditions. No hips formed until approximately the third year of growth. I am studying one of these seedlings now. This does give one hope for future utilization as seed parent.
Ploidy is defined as "A multiple of the basic number of chromosomes in a cell".
Rosa banksia like most roses indigenous to temperate regions is diploid, that is possessing 14 chromosomes. Most modern roses are tetraploid, possessing 28 chromosomes like roses found in Europe before modern hybridization began to take place. Crosses between these ploidy types usually results in sterile triploid offspring or those of limited fertility possessing 21 chromosomes.
Early in 2005 I contacted David Zlesak to see if would consider doing root tip squash analysis of both 'Lila Banks' and 'Riverbanks' to determine ploidy using visual evidence offered through scanning electron microscope images.
'Lila Banks' was determined to be triploid, possessing 21 chromosomes. As 'Antoine Rivoire' is tetraploid the progeny of the offspring using 'Lila Banks' pollen would be uncertain depending upon what kind of pollen is being produced. 'Riverbanks' was also determined to be triploid. One can assume from these findings that at least in the case of 'Riverbanks', reduced diploid pollen from 'Lila Banks' was produced.
Further experimentation is warranted by use of diploid seed parents to determine if production of fully fertile diploid offspring is possible using pollen of 'Lila Banks'. It may well be the case that a variety of pollen ploidy types are being produced. David Zlesak has kindly offered to examine pollen of both 'Lila Banks' and 'Riverbanks' to make determination as to what pollen types are being produced.
This season of 2005 'Lila Banks' pollen was used in many crosses using several garden varieties as seed parent. Resulting seedlings will be screened for fertility and future use in reciprocal crosses using 'Riverbanks'. 'Riverbanks' shows promise as seed parent. Several open pollinated hips are maturing at this time. More experimentation using diploid seed parents is warranted.
It is my hope that other evergreen species hybrids can be utilized for crosses involving banksia hybrids. Most notably crosses involving bracteata and clinophylla hybrids hold promise in producing disease resistant evergreen Winter blooming varieties suited to warm winter climates.
Hybridizers I'd most like to emulate include Ralph Moore for his work with R. bracteata, Alister Clarke for his work with R. gigantea and most notably Dr. Viru Viraraghavan for his work with R. clinophylla.
I was both surprised and pleased to discover that Dr. Viraraghavan and hi Wife Girija began breeding roses with very similar goals in mind but beginning some twenty plus years ago. These goals include the production of heat and disease resistant evergreen Winter blooming shrubs incorporating fragrance and as much as possible a pricklefree nature.
Through information gathered from Fred Boutin I now know that wild forms of R. banksias are normally heavily armed with prickles. Some have theorized that pricklefree garden forms of R. banksias are in fact be ancient selections of probable somatic mutations so may not hold as much promise for breeding smooth roses as hoped.
Crosses involving 'Lila Banks' and 'Riverbanks' as seed parent should be possible, a back cross using R. banksia lutea or lutescens would be a future goal in order to gain a greater percentage of banksia genes and extended color range in offspring.
As a final note I'd like to include that I think it ironic that this particular course of research and events was brought about by one individual seeking, 'Grey Pearl'. All current banksias crosses descend from 'Grey Pearl' through 'Lilac Charm', and all current banksias hybrids might also just as easily be labeled californica hybrids as the percentage of genes represent by this species may be greater than that offered by Rosa banksia banksia.
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