The history of azalea breeding in Europe and its influence on contemporary American hybrid varieties

How a Belgian variety from the 1890s named ‘Vervaeneana’ connects the old with the new

The first evergreen azalea said to arrive in Europe is ‘Breynii’ in 1680. This plant was described by Jacob Breyne, a Polish mercant and naturalist, in his Prodomi in 1739.¹ He observed this plant in estate of Hieronymus van Beverningh near Leiden, the Netherlands. The description is brief, and does not include a drawing. It includes the comment 'This is one of the rarest and most elegant things that we have ever seen'.

In the early 1800s, there was a culture of collecting exotic plants all acrros western Europe. Greenhouses, exhibitions, and botanical journals payed a key role. The enthusiasts and professionals displayed a good understanding on the concepts of wild species, cultivars, and hybrid crossbreeding, and the distinction between evergreen azaleas, decidious azaleas, and rhododendron. All evergreen azaleas were recognized as ‘Azalea indica’ or 'the Chinese azalea'.

The first evergreen azalea pictured in a journal was ‘Azalea indica’ in Curtis Botanical Magazine in 1812 (figure 1).² This almost certainly shows some form of Rhododendron simsii. I say this because of the 10 stamen, the small red flower, the blotch being a darker shade of red rather than purple, and the relatively large leaves. This original 'Azalea indica' is described as being a hardy plant, but that its major flaw was a poor arragement of flowers and a loose branchy plant habit.³ A trait that seems to confirm a wildtype origin of this selection, rather than a garden hybrid form improved specifically for horticulture. The key quality of ‘Azalea indica’ is that it blooms early and it would play a key role in obtaining varieties that could be forced to bloom during winter and finally as ealy as late summer.

The second azalea introduced in 1819 was ‘Azalea Ledifolia’ (figure 2), which matches the description of what we today call R.mucronatum almost perfeclty.⁴ This species provided large flowers, strong blotches, purple colours, and scented flowers to future azalea varieties. This plant is also known as ‘Azalea alba’ and similar forms were later named ‘Yodogawa’ and ‘Noordtianum’.

Two more new azalea's appeared in the Edwards Botanical Register of 1834, ‘Azalea lateratia’ (figure 3) and ‘Azalea lateriata variagatum’ (figure 4).⁵ The author makes it clear that the leaves and plant habit on both plants are identical, but the flower colours being different. Both plants are highly likely to be Rhododendron indicum or some satsuki hybrids dominanted by R.indicum, since these azaleas have 5 stamen and are described as being more compact and low growing than the other Azalea indica. ‘Variegata’ has often been refered to as ‘Matsushima’, a very old and famed satsuki, though I was not able to find a source that stated that this plant was known under the name ‘Matsushima’ in Japan. ‘Matsushima’ is a known satsuki cultivar in Japan that fits the description of ‘Variegata’. Another form of R.indicum was introduced as 'Azalea Danielsiana', which most likely is the same plant as 'Macranthum'. These varieties were described as very low growing bushy plants, but less woody and hardy than the other Azalea indica. The flowers of these varieties, and their direct offpsring, were considered to be superior in their delicate bicolours and symmetrical flowers. For the first few decades, the goal of azalea breeders was to obtain varieties that had the quality of the blooms of 'Variegata', but the hardy natura and rate of growth of some of the other Azalea indica.

‘Président Claeys’ is a sport of ‘Variegata’, named by Eduard van der Cruyssen in Belgium, 1858. In the US, this plant's name changed to ‘President Clay’ (figure 5). Some places in the US still sell ‘President Clay’ however, many very old cultivars were eventually mislabeled or misnamed, as such mistakes couldn't be easily corrected. The true ‘President Clay’ should have the jewel border pattern with 5 stamen, and a plant habit similar to R.indicum. Azaleas with bicolour patterns often eventually become solid coloured sports. So without correct propagation procedures and checks, it is likely for ‘President Clay’ label to be used for a solid pink sports of the origial plants.

A final very important azalea pictured in these journals is ‘Azalea phoeniceum’ (figure 6).⁶ This azalea seems very similar or maybe identical to ‘Omurasaki’, the Hirado azalea from Southern Japan. Therefore, ‘Phoeniceum’ is a R.pulchrum azalea. R.pulchrum azaleas are thought to be hybrids of R.scabrum and R.mucronatum. ‘Phoeniceum’ is vigerous grower and was used as a grafting stock for most Belgian azaleas for many decades, until it was replaced by ‘Coccinta’, ‘Hexe’ and later ‘Euratom’, before finally Belgian indica varieties could be mass produced on their own roots. The genetics of ‘Phoeniceum’ created stronger growing plants, with large leaves and good root growth, as well as large flowers and purple colours. This azalea is said to be very similar to the Japanese cultivar ‘Omurasaki’ and American Southern Indica varieties ‘George L. Taber’ and ‘GG. Gerbing’ are very likely to be sports of either ‘Phoeniceum’ or ‘Omurasaki’.

Immediately after the introduction of these 5 plants from Asia, we get records of new seedlings being raised. It seems that the horticulture community in western Europe during the early 19th century was primed for new azaleas. Skilled nurserymen that had honed their craft on hybridizing tulips, carnations and orchids, became smitted by the new azaleas and immediately went to work on producing more plants.^7,8 The first new variety was raised in 1830 by M Smith and was named ‘Pulchra’ (figure 7) and is suspected to be a hybrid of ‘Ledifolia’ and R.simsii. The The Florist Fruitist Garden Miscellany journal from 1853 already lists 81 varieties of ‘Azalea indica’, including brief descriptions, but lacking any drawings.⁹ Most of the initial seedlings seem to have been produced in England. William Smith of Norbiton, today a part of London, produced his new varieties in the 1930's. Some of them are said to have been marketed by Knight and Perry. The names of the most important of these new varities by these three Englishmen are: ‘Apollo’, ‘Broughtonii’, ‘Exquisita’, ‘Optimum’, ‘Punctatum’, ‘Smithii’ and ‘Speciosum’.

Another notable variety from England during that time is, ‘Glendstanesii’, introduced by W. Rollisson & Sons. ‘Pride of Dorking’, ‘Danielsianum’ and ‘Cavendishii’ are three more important azaleas introduced at this time in England, but their hybridizers are unknown. Finally, we have ‘Fielder's White’ by Fielder. In 1850, Robert Fortune introduced several more azaleas from China: ‘Vittatum’, ‘Vittatum Punctatum’, ‘Bealei’, ‘Narcissiflora’ and ‘Crispiflora’. Some of these azaleas were introduced in England by Standish & Noble.

Another early hybridizer of azaleas in England was J.Ivery. He obtained two azaleas that he named ‘Iveryana’ and ‘Formosum’. ‘Ivaryana’ has an unknown parentage, but it is most likely a seedling of ‘Variegata’. ‘Formosum’ has also become known as ‘Formosa’, ‘Lateritium Formosum’ and ‘Conquerer’, suggesting it is similar to the original ‘Lateratia’ and thus also a satsuki hybrid. In Belgium during 1860, a sport of ‘Formosum’ was named as ‘Dieudonné Spae’ (figure 8) and displayed in L'Illustration Horticole 1860.¹⁰ It shows a flower with a jewel border bicolour pattern and 5 stamen, confirming its satsuki heritage. Much later on in time in the US, ‘Formosa’ would produce a sport that would be named ‘Judge Solomon’.

Many azalea varieties were given different names or gained synonyms at some later point. ‘Cavendishii’ is also known as ‘Lady Cavendish’. ‘Smithii’ is probably also known as ‘Smithii Coccinea’, ‘Concinnum’, and ‘Rawsonii’. With this, we have identified the origins of many of the Southern Indica azaleas in the Deep South of the US. Some of them, like ‘Iveryana’ and ‘Pride of Dorking’ are still available from the nursery trade. And in Europe, all of these varieties set the stage for the development of the florist azalea, or Belgian indica azalea. It seems that from the 1850s onward, very little new varieties were introduced from Asia. And that the varieties named above formed the genetic base for a 150-year long breeding project.

Only in very few cases was a parentage provided for these new varieties. For ‘Speciosum’, we know R.indicum was pollinated with pollen from ‘Phoeniceum’, as this is stated in the description that accomynies the drawing in British Flower Garden series 2 Vol3 of 1835. ‘Exquisita’ (figure 9) was uses as a seed parent by J.Ivery, with ‘Iveryana’ as the pollen parent, to obtain ‘Criterion’. Furthermore, Mr.Ivery used ‘Iveryana’ as the seed parent with ‘Formosa’ to obtain ‘Admiration’. A drawing from the Florist Fruitist & Garden Miscellany of 1852 shows ‘Admiration’ to be a white flower with pink variegation, while ‘Criterion’ is a jewel border bicolour (figures 10).¹¹

In the 1840's and 1850s, many of these English varieties made their way to continential Europe, where plant breeders immediately generated a burst of new varieties. Sadly, for almost all of them we do not have any parentage. One of the earliest Belgian varieties for which a parentage, is ‘Versicolor’ (figure 11). Mr. Van Geersdale obtained this new variety in 1839 by cross-breeding ‘Speciosum’ with pollen from ‘Variegata’. Some of the other varieties initially produced in Belgium during that time are ‘Alexandre II’ (figure 12), ‘Glorie de Belgique’, and ‘Comte de Hainaut’. All these azaleas have no known parents and no known offspring.

Some of the oldest known ancestors of the current Belgian indica azaleas are ‘Duc de Nassau’, ‘Deutsche Perle’ (figure 13), ‘Niobe’, ‘Baronne de Vrière’ and its sport ‘Professeur Wolters’, and ‘Madame van der Cruyssen’. These were some of the most popular varieties in the early 20th century, but we cannot link them back to the earliest azalea indica. ‘Duc de Nassau’ was obtained by the brothers Mardner in Germany in 1854 and it is a keystone variety for present day florist azaleas. It's parentage is not known. Dr.Scheerlinck wrote the following about ‘Duc de Nassau’ in his 1938 book: "Variety of the very first rank, very large single flowers with wavy petals. Strong growth. This variety has contributed significantly to improving the azalea indica. This variety was produced at a large scale."¹² In 1870, Louis van Houtte obtained a sport of ‘Duc de Nassau’ that he named ‘Alice’ (figure 14). A drawing of ‘Alice’ appeared in L'Illustration Horticole, Vol. 23 of 1876.¹³

From these ancestor varieties, newer varieties like ‘Hexe’, ‘Paul Schäme’ and ‘Madame Petrick’ were obtained. At this point in history, during the 1870's and 1880's, German breeders of azaleas were more succesful than the Belgians. Dr.ir.Heursel explains this by noting that the German breeders managed to produce plants that were more profitable rather than more beautiful or unique.¹⁴ These newer varieties were even more suitable suitable for greenhouse forcing them to bloom earlier and ealier in the season. This allowed azalea nurseries to produce a product that was in bloom during the Christmas holidays, which made them commercially much more succesful. In the 1960s where ‘Hellmut Vogel’ variety was obtained, florist azaleas could be forced as early as August. Thanks to this huge hybridization effort, florist azaleas can forced to bloom from August to May. This in contrast to the origical Azalea indica, that only bloomed inside a greenhouse in Februari or March. As a result, a lot of the R.indicum and R.mucronatum traits were lost.

Rather than fanning out in diversity, the solid-coloured, double flower that is a representation of a R.simsii x ‘Phoeniceum’ hybrid, became the dominant type of Belgian indica azalea. Varieties that are poorly greenhouse-forced were abandoned, even though for the earliest varieties that were most popular, their drawings show a clear satsuki-infuence. It is important to note that consumers would buy these azaleas just as they were about to bloom, but during the winter period. The best varieties can bloom indoors for up to 8 weeks. In this way, the Belgian indica would compete directly with cut flowers. And not with other garden or landscaping plants. Once the azalea would finish blooming, the consumer would usually just throw it away. Ourdoors, these would usually not survive. While selection requirements for the breeding of new varieties were very strict, the criteria of a plant doing well in a garden for many years, was clearly not one of them. Except for some azalea breeding in Italy, around the lake Lake Maggiore area, the Azalea indica as a outdoor garden plant did also not gain traction in warmer parts of Europe.¹⁵ Today, the Ghent azalea is an officially recognized Regional Product by the European Union. About 85% of all Belgian indica azaleas worldwide are produced in the Ghent area, with most greenhouse nurseries in the town of Lochristi, just Northeast of Ghent. And after many years of decline, the market for Belgian indica seems to have stabilized.

But going back to the earlier days, there is one other variety obtained in 1884 for which a parentage is given, namely ‘Vervaeneana’ (figure 15 and 17), obtained by Joseph Vervaene in Belgium, 1884. The parentage is generally given as ‘Koningin der Weissen’ x ‘Versicolor’. The story goes that an unnamed seedling from this crossbreeding gave rise to two sports. One was named ‘Vervaeneana’, the other ‘Pharailde Mathilde’ (figure 16). An slightly different parentage is given by dr. Scheerlinck. He mentions that it was actually a sport of ‘Versicolor’, named ‘Comte Charles de Kerchove de Denterghem’ that was used as the seed parent, with ‘Koningin der Weissen’ as the pollen parent.¹² Dr. also Scheerlinck describes 'Vervaneana' in the following way: "The world famous ‘Vervaeneana’ wins the highest awards in every exhibition where it is displayed and has almost let to the disappearance of all other other salmon-coloured varieties with white margins.¹²

‘Vervaeneana’ was highly popular until the middle of the 20th century. Today, this variety is no longer producer commercially. dr.ir.Jozef Heursel has estimated that successful azalea indica varieties have a lifetime of about 40 years.¹⁴ After that time, they are usually superseded by newer varieties. And because azalea indica cannot reliably be grown outdoors in gardens, most of the obselete varieties have gone extinct. Only those varieties that are still grown in places with warmer climates, like the Deep South of the US, Australia or New Zealand, have avoided extinction. As have varieties that have managed to be added to the genetic collection of the Belgian or German government institutes, set up specifically to prevent the extinction of these old but superseded varieties.

‘Vervaeneana’ has also played a role in developing garden azalea varieties. Robert Gartrell used ‘Vervaeneana’ as a parent in the creation of some of his Robin Hill varieties. ‘Nancy of Robinhill’ (figure 19) is one of his most popular varieties, and has ‘Vervaeneana’ as the seed parent. ‘Lady Louise’ was the pollen parent in this cross, and is itself a result of the very hardy Gable azalea ‘Louise Gable’ and the Chugai satsuki ‘Tamagiku’. ‘Nancy of Robinhill’ clearly inherited some of the qualities that the Belgians so prized in ‘Vervaeneana’. More recently, Bob Stewart used ‘Nancy of Robinhill’ as a parent in his azalea breeding. He used ‘Vervaeneana’ together with the azalea code-named CB1 as a seed parent. CB1 is a discarded seedling from the University of Maryland breeding program that was resued by Cliff Brown. It should be noted that the Universty of Maryland started their breeding project by hybridizing again the same ‘Vervaeneana’ with pollen of several other azaleas. Which means CB1 as well is a descendant of ‘Vervaeneana’.¹⁶ One of his results is ‘April Elaine Sanborn’ (figure 20), which has some of the delicate pink colourings of ‘Vervaeneana’. This Stewart azalea can therefore be directly linked to ‘Variagata', one of the first documented evergreen azaleas, as described in English horticultural journals of the early 19th century.

Bob Stewart was not the only American that used ‘Nancy of Robinhill’ in their breeding. Colonel Pete Vines is the creator of the Holly Springs hybrid group. He hybridized ‘Nancy of Robinhill’ with 'Shinnyo-no-Tsuki' (figure 21), a famous satsuki known for it's large bicolour flowers and the subject of a The Azalean article.¹⁷ One of his results he named ‘Holly Springs Double Delight’ (figure 22), a variety that has ‘Vervaeneana’ double blooms, but with a more uniform salmon colour.

Because ‘Vervaeneana’ was grown by many European nurseries for a long time, probably resulting in millions of plants, it has also produced many sports. One of them is ‘Albert-Elisabeth’ (figure 18). Howard Kerrigan used 'Albert-Elisabeth' as a seed parent in combination with ‘Captain Blood’, which allowed him to produce the striking ‘Gay Paree’ (figure 23). Joe Klimavcz used ‘Gay Paree’ in his hybridizing, first crossbreeding it with ‘Mrs Nancy Dipple’ and combining that result with another of his seedlings, to finally produce ‘Andrea Jeanne’ (figure 24). ‘Andrea Jeanne’ actually also has ‘Vittatum’ as a great-grandparent and, through Klupinger's ‘Satellite’ it has ‘Deutsche Perle’ as a great-great-great grandparent. And hidden even deeper in the ancestor tree, there are also two occurences of ‘Hexe’. This hybridizing effort relies strongly on the breeding work done by English, Belgian and German azalea breeders, producing a landscape azalea with impressive flowers and a reliable plant habit.

Interestingly enough, back in Europe there has been little crossover between garden obtusum varieties, and the Azalea indica. Additionally, satsuki and Hirado varieties have been extremely rare. Both Azalea indica and Azalea japonica have filled their own highly specialized little niche. And there has not been much room for experimentation. This may be due to a lack of amateur azalea breeders. Because of this, European gardens currently lack the large, bicolour or variegated flowers commonly found in both the US and Japan. Those varieties that we do have here today actually came from the US. Namely, ‘Nancy of Robinhill’, ‘Margeret Douglas’, ‘Autumn Sunburst’ and ‘Hilda Niblett’. As winters have become warmer and the growing season has extended, because of climate change, many more parts of Europe now have milder winters and longer growing seasons as compared to the late 19th century. For Europe, introducing new varieties from both Japan and the US, together with more experimentation, creativity, and wider crosses in our local azalea breeding, could help improve the local diversity of azaleas. While I am very enthusiastic about azaleas myself, it is not quite clear if there is a consumer demand for more expensive and exclusive evergreen azaleas. Possibly, the consumer en large actually prefers cheap, durable, easy, but maybe also somewhat boring landscape plants. There will also be competition from other flowering plants. Especially competition from hydrangia's seems relevant, as they fill a similar niche as azaleas. Hydrangia's are probaby faster and easier to produce, more forgiving, and their blooms are very impressive, long-lasting and durable. But if there is enough consumer demand for unique azaleas, maybe this can bring to culmination inside our gardens, the enourmous breeding efforts by the English, Belgian, and German azalea pioneers.