Historical cultivars of Allium cepa L. (Aggregatum-Group) introduced to Sweden 1830–1860

This study presents the plant material of A. cepa L. Aggregatum-Group introduced and spread in Sweden between 1830 and 1860. The plant material exemplifies different principles regarding the denominations and shows the range of cultons available in the north of Europe by the time, but also examples of domestic local cultivars. It is essential to deepen the knowledge of the plant material and the name use connected to cultons spread in the nineteenth century. Historical records of old growing systems and propagation methods add valuable insights of the preservation values tied to the genetic diversity of the gene pool for future breeding. Differing practices and principles for distinguishing between potato onions, shallots and onions in European countries have sometimes made it difficult to understand historical records. The results of this study shows that shallot and potato onions, later mainly vegetatively propagated, were already in the nineteenth century occasionally propagated and spread by true seed in Europe. In addition, a Russian growing system with a true seed generation was found in literature. The article concludes that knowledge of older cultivation systems and introduction history deepens the link between the cultural-historical and the biological conservation values of plant material in long time preservation. Gene bank accessions may not only be valuable in breeding but also utilized and preserved as part of a biological or green heritage.


Introductuion
Heirloom cultivars of multiplying onion (Allium cepa Aggregatum-Group.), known as potatislök [potato onion] or shallots and by local names, were collected and evaluated from all over Sweden in nation-wide surveys conducted by the Swedish National Programme for Diversity of Cultivated Plants (POM) during 2002-2010.The onions where often described as especially well suited for storage over winter and are preserved by the National gene bank (Strese andDe Vahl 2018).
The collected onions were believed to originate from plant material that had been cultivated in the countryside for a long time (Leino andHagenblad 2014) and has been found to be genetically diverse compared to accessions from Fennoscandia (Leino et al. 2018).
Knowledge of older cultivation systems, introduction history and folk taxonomy deepens the link between the cultural-historical and biological conservation values of the plant material that has been documented and preserved within the Programme for Diversity of Cultivated Plants (De Vahl 2020).Further, traditional uses and practices of edible cultivated Allium species in Sweden has been described by de Vahl and Svanberg (2022) including the older cultural descriptions promoting autumn planting of both shallots and the more hard-to-identify cultural forms of onions called johannislök (saint john's onion) and jacobslök (saint jacob's onion) that was advocated until the mid-nineteenth century in Swedish garden literature (ibid).
According to Rabinowitch (Rabinowitch 2021), sources of genetic variability includes generations of epigenetic variants, accumulation of mutation in clonally-propagated cultivars, and selections for adaptation to various environments.
The results of the genetic survey of European gene bank accessions of multiplying onions suggest that home gardens, might have had an important role as plant genetic diversity hotspots, serving as a preserving environment for a surprisingly high number of unique genotypes from different European countries (Ruņgís et al. 2020).
The collaborations regarding Allium of the European Cooperative Programme for Plant Genetic Resources (ECPGR-Allium) had also documented older cultivation systems such as the four year seed-propagation cycle known from villages near Lake Peipsi, Estonia where this species has been propagated by seed since the seventeenth century (Ruņgís et al. 2020).
This paper aimed at deepen the knowledge of plant material and early cultivars in trade in Northern Europe during the 19th century with emphasis on the plant material imported and spread by the Swedish garden association founded in 1832.The paper also aimed to give an Swedish example of how knowledge of horticultural history can be helpful in explicating preservation values for living germplasm collections.Differing practices and principles regarding distinguishing between potato onions, shallots and onions in European countries has made it di cult to understand historical records of early trade and spread of plant material.By highlighting historical examples from different countries, The aim was to deepen the knowledge of how historical source regarding multiplying onion can be analyzed and understood.

Methods
For this study the yearbooks of the Swedish garden Association [Svenska Trädgårdsföreningen] 1834-1863 and the volumes of the journal Tidning för Trädgårdsodlare published 1862-1901 were studied.Supplementary information were found through searches in the digitized historical newspapers available through the Swedish Royal Library and in the archive material from the Swedish Garden Association which is located at the National Archives 'library and the Royal Swedish Academy of Sciences' archives.In digitized material used, many different trivial names were found in reviewed literature as keywords.
Accessibility through digitization made it possible to search for relevant information though a relatively wide range of Swedish material.However, the source material analyzed from other European countries are narrower and incomplete and is therefore used as qualitative records supplementing the results analyzed in a Swedish perspective.Digitized seed catalogues of Haage and Schmidt 1869-1920 was studied besides digitized volumes of French Vilmorin-Andrieux et Cie-yearbooks and English literature, translations of French sources and correspondence in garden magazines concerning Multiplying Onions in the 19th century.

Results
Results of the study are presented in Table 1-4.The German source material presented in Table 1 are the digitized plant catalogues of Haage & Schmidt.Table 2 consists of data from the distribution catalogues of the Swedish garden association and these tables descries the propagation methods by seed or by sets and the span of years each cultivar is sold, spread or descried in literature.Table 3 and 4 on the other hand describe data from literature and do not hold information of propagation methods.On the other hand, the literature often aim at pointing out known synonyms or denominations in other languages at the times.
The literature study show that several cultivars of shallots were imported, cultivated and distributed in Sweden long time before the rst literature data regarding a certain form of shallots, especially well adapted to Nordic cultivation conditions, was spread by famous Swedish gardeners Olof Eneroth and Daniel Müller in the mid-1800s (Table 2).The landrace cultivar 'Leksand' was also grown in the garden of the Swedish Garden Association in 1859 together with a number of other named cultivars (Fig. 1).The review of source material from France, Germany and England showed that several cultivars were known and described at the time and that different cultivars were named after their presumed provenance (Table 1, Table 3 Table 4).The popular names used show contradictory views on the status of shallots as their own "true" species at the time, making the distinction between potato onions and shallots inconsistent and differing in European countries during the 19th century.1. Different principles of distinguishing between shallots and Potato Onion.
To understand the rise of several cultivars of multiplying onion in the 19th century, a few examples of different principles in distinguishing and naming cultons were given from Germany, Great Britain, France and Sweden.
In French, English and American literature from the 19th century, it is possible to follow the spread development of knowledge regarding cultivars of shallots based on the plant material described in the French seed company Vilmorin-Andrieux et Cie's publications (Table 3-4).
In 1844 'Echalote de jersey' was described as a new species or cultivar in France that differed mainly on its earlyness and leaf color (Poiteau 1844).Discussions and misunderstanding concerning the new cultivars.
There are examples of how the many new cultivars described in the garden literature during the 19th century were met with skepticism and created misunderstandings.In 1859, British Robert Thompson, at Royal Horticultural Gardens in Chiswick claimed in The Gardener's Assistant that there were in fact only four known cultivars of shallots but that they often degenerated into the common type again within 2-3 years (Thompson 1859).
In England, the ability of shallots to ower and set seeds was central to the discussion around the new cultivars.In The British journal, The journal of horticulture, cottage gardener, and home farmer A. F. Barron of Chiswick 1883 elaborated on various synonymous cultivar names used for the two actual cultivars of true shallots that he, after many years of cultivation experiments, could recognize.These were 'Common', with small bulbs, and 'Large Brown'.The later with the synonymous names 'New Russian', 'Small Red', 'Large Red', 'Large Russian', and 'Stuart & Mein's Exhibition Shallot ' (Barron 1883).According to the author, there are two more cultivars, but unlike the "true shallots", they set plenty of seeds: 'Jersey Giant Red Shallots' and the 'Jersey Silver-skin'.The propensity to set seeds, according to Barron, meant that these should not be considered as Allium ascalonicum but as an inferior form of common onion A.cepa, similar to "potato onions".Further, Barron pointed out the unfortunate mistake in that Vilmorin gave 'Jersey' as a synonym for 'Russian Shallot' while 'Russian Shallot' in England and Scotland was considered a synonym for "true" shallots, more speci cally the cultivar 'Large Brown'(Barron 1883).

True seeds of both Potato onions and in Germany
In German price lists during the latter part of the 19th century, both true seeds and sets were sold of shallots and potato onions [Kartoffel-Zwiebeln] (Table 1).In Haage & Schmidt's catalog 1869 seeds of the cultivars 'Grosse von Jersey' and 'Dänishe, echt' and of the potato onion cultivars 'Grosse Gelbe' and 'Silberweisse' are for sale.Sets are also sold of "common large shallots" and 'Grosse Dänishe (russ)'.

Further cultivars were sold and listed as potato onions
The range of cultivars varied slightly over the following decades where different descriptive name variants were used both for seeds and for sets (Table 1).

Early name forms of potato onions
Written evidence for the trivial name potato onion for multiplying onion is available from Germany from 1795, as 1795).In Swedish literature Nils Lilja published the name "potatoesonion" in his Flora in 1839, but already in 1834 the "Egyptian potato onion" was shown at the newly started Swedish Garden Association's exhibition according to newspaper articles and the association's yearbook (Lilja 1842; Rosenblad 1834).The name undoubtedly refers to the onion's way of multiply one set to several onions, similar to potatoes.The popular spread of the name cannot have preceded the popularization of potatoes (Solanum tuberosum) and it is likely that the potato onion, similar to the potato, came to be regarded as a novelty.However, Siemers, an Swedish gardener with German and Danish background used the name for the small onions achieved the following year when planting the yellow Spanish onion in autumn (Siemers 1844).He used the term "yellow spanish onion" as a category including all yellow cultivars of seed-propagated Allium cepa.
6.An Egyptian onion with poor shelf life?
In a letter to the British Horticultural Society of London dated 1818, the gardener John Maher at Arundel Castle in Norfolk wrote about what he calls "Under Ground-onion" but according to the author, it was called "potato onion" by others (Maher 1822).He argued against those who called these onions "Egyptian onion" and explained that he grew the onion in London already in 1796, two years before the Battle of the Nile, when others claimed that the British rst came across the onion after defeating the French (McIntosh 1855).Maher further described how the smallest bulbs were used as sets and that soil was raised around the bulbs, as done for potatoes, after they had started to sprout when planted in February.The bulbs were then harvested in July and according to Maher, this crop was common in the west of England where tradition dictates that they should be planted on the shortest day of the year and harvested at the longest of the year.Furthermore, it was stated that a gardener from Exeter in the southwest England announced that this crop had been known and cultivated for 20 years (Maher 1822) .
In the same published correspondence, the gardener at the Horticultural Society of London, Charles Strachan, also described the potato onion as a crop whose best quality was that it gave harvest in early summer, before other onions are ready for harvest.He meant that it was widely regarded as a variant of Allium cepa and is a strong onion (Strachan 1822).According to Woodward (1996) the potato onion was spread to the United States in 1820.The American farmer's encyclopedia of 1844 stated that the potato onion was introduced to Scotland by Captain Burn of Edingburgh and accordingly known as 'The Burn Onion' (Johnson andEmerson 1844).
In French literature, L'ognon patate was often described as a horticultural form of Allium cepa in the 19th century.It was missing in Le Bon Jardinier 1809 and 1819 but was described as a novelty in 1825 where the name "d'Ognon sous terre" was also found (Poiteau 1809; Poiteau andAudot 1817, 1819, 1825).In 1837, winter storage of the onions was described as something that required very dry and cold conditions along with an additional advice on leaving some of the wilted leafs during storage, from an corresponding reader (Poiteau 1837).
The potato onion sometimes shared the pre-epithet "Egyptian" with tree onion, Allium x proliferum during the 19th century.In the French Description des plantes potagères four known cultivars were described as shallots (A.ascalonicum), while both "Ognon d'egypte" [tree onion] and "Ognon Patate" [potato onion] were described as Allium cepa (Description des plantes potagères Description des plantes potagères 1856) Just as in Le Bon Jardinier from 1825 the potato onion was described as a possible culta of the "Egyptian Walking Onion" (Poiteau andAudot 1825).The potato onion did neither produce seeds nor bulbils, did ripen early but keeped poorly in storage according to the same French description.
A similar statement about poor storability was given in the extensive North American price list Vick's ower and vegetable garden published in 1878 (Vick 1878).The potato onion was here called 'English Potato Onion' and should be "the best underground variety ".It was advocated in parts of the United States where it was problematic to grow onions from seed and it was claimed to be the onion that was most frequently sold in bundles in the spring at markets.If the onions were instead allowed to grow further through the summer, large onions were formed and could be used as a seed next year to get many small onions for sale in spring.The storage method proposed was to let the onion freeze in the winter and then cover with straw so they stayed frozen.Also from Germany there were records that indicate an mixing of tree onions and potato onions.Meeting minutes from Dresden in 1836 stated that the chairman had received four potato onions from Hamburg that had multiplied to 22 bulbs, but that three of them also formed up to 20 bulbills in the in orescence (Anonym 1836).

"Moscovite Potato Onion" or Russian Shallots?
In documents from Des Vereins zur Beförderung des Gartenbaues in den Königlich Preußischen Staaten 1839 there was an article by gardener Ohm describing the "Moscovite potato onion" [Kartoffelzwiebel] with "Russian Shallot" as a synonymous name (Ohm 1839).It was described as a cultivar tastier than ordinary onions but it was not distinguished from shallots.During the second half of the 19th century, various cultivars were marketed and distributed as potato onions in Germany, often with cultivar names describing the country of origin and the color on the onion (Table 1).Potato onions from Denmark, Russia, England and Spain were described or/and spread.(Anonym 1839; Anonym "Kleine, vermischte nachrichten."1844).In the Berlin garden weekly Wochenschrift des fereines zur Beförderung des Gartenbaues in den Königl.Prenssischen Staaten für Gärtnerei und P anzenkunde, a report from a plant exhibition in 1867 tells that gardener Pasewaldt displayed two onion cultivars.However, the rst one called 'Pommersche Schalotte', turned out to be the "usual Danish", according to the report.The other was ordinary potato onion (Verein zur Beförderung des Gartenbaues in den Preussischen 1867).
It is obvious that a number of named cultivars was known and spread in Germany during the 19 th century.While the English gardeners tried to group and separate cultivar of Shallots and potato onions through their ability to ower, it is more unclear if and how German gardeners and writers distinguished betweeen potato onions and shallots at the time.

Shallots from seed?
There are examples of how shallots were historically propagated by seed, although cultivation descriptions generally describe shallots as vegetatively propagated.In 1694 Swedish author Åke Rålamb described shallots: "The seed comes from Italy and is sown like the other Onion seeds " (Rålamb 1694).
In the British magazine Gardeners Chronicle and Agricultural Gazette correspondence between several growers describing how they successfully grew shallots from seed can be found.John May from The Gardens, West eld, Hayling Island, shared his experience of how growing shallots both from seed and from sets gave him the impression that the plant material of both potatoes, potato onions and shallots should be replaced regularly from other regions to prevent plant diseases (May 1872).When plant material is spread this way, the writer believes that the bolting frequency of the onion is increasing.Also Chas.Was.Perry, from The Cedars, Castle Bromwich, in the same magazine claimed that cultivation of shallots from seed were less problematic and could give three times as large yields (Perry 1872).The opposite view also emerges from the correspondence.The reader C. B. S. Jersey found that seeds of the cultivar spread as 'Jersey' instead of forming large onions formed clusters with many small bulbs, which in his opinion is uneconomical and di cult to handle in the kitchen (Jersey 1872).
Later that year, B. R. Davis of Yeovil described how he for many years had tried to achieve the cultivar 'Jersey'.When he nally got the true sets of the cultivar from Germany it turned out that all seedlings owered and produced seed (Davis 1872) .
As previously shown, seeds of both shallots and various types of potato onions were spread in Germany during the 19th century (Table 1).Further, Charles McIntosh in The Book of Garden describes how Messrs. Hardy and Sons, from Essex from shallot seeds obtained onions with many different characteristics, with offspring similar to both potato onions and ordinary onions (McIntosh 1855).After the trial cultivation at the Horticultural Society of London, variations in both shape and color where noted, and the author believed there was a good basis for further selection to obtain a cultivar with good storage capacity.
In 1920, Swedish-Finish author Ossian Lundén gave an interesting insight to how seed cultivation of "onion sets" in southern Russia was carried out for export to Finland (Lundén 1920).The Russian onions sold to Finland were described as autumn-harvested onions from seeds sown in early spring.In southern Russia these sets where then planted to give "food onions" in year two when the onions formed clusters.
Further, the most beautiful, medium-sized, and most solid onions of these where chosen for next spring to be replanted and give seed harvest on autumn year three.According to Lundén, there were no exports of true seeds from Russia.
Already in 1808 Swedish author Carl Ihström described how multiplying onions could be grown from seed The desciptions of Lundén and Ihström corresponds with the Russian cultivation system combining vegetative and sexual reproduction also described by Bednarz (1994).From Northern Russia a tradition with small onions used as sets is described.The seed propagation takes place regularly every 5-7 years (Ibid).A possible relict of a similar growing system were found in modern times at Estonian Peipsi Lake where local growing tradition of multiplying onions included a seed generation every third or forth year (Ruņgís et al. 2020).The plant material in the Estonian cultivation system was found to be genetically heterogeneous and the genetic variation within the plant material from the region studied was greater than the variation in the older cultivars of shallots preserved in European gene bank collections at a whole, which was explained by the deliberate incrossing of ordinary onions (A.cepa) occurred (Ruņgís et al. 2020).

Discussion
Litterature studies on onion cultivation in northern Sweden indicates that the shallots introduced and spread was made popular rst in the 19th century, which also corresponds to a statement from Scania in south of Sweden where 'Asian Red Onion' in 1822 was presented as a novelty (De Vahl 2020).Like the potato, it was propagated vegetatively and would therefore be of bene t to poor small scale farmers.In literature studies, older culture descriptions have been described by de Vahl & Svanberg (2022).Here it is concluded that autumn planting of both shallots and the hard-to-identify cultural forms of onions called by names like johannislök and jacobslök is advocated until the mid-19th century, while the occurrence of culture descriptions of a certain kind of shallots especially suitable for northern conditions can be found rst in the 1850's.During the early part of the 19th century the potato onion are often described in the literature with the pre x Egyptian and mix-ups also occur with the hybrid tree onion A. x proliferum, which for a long time goes by the common name "Egyptisk luftlök" in Swedish.According to Täckholm & Drar(1954) neither the tree onion nor the potato onion (referred to as A. v. aggregatum) were known in cultivation from Egypt.However a cultivar of A. cepa called 'El Kirdási' said to form two or more small onions with good storability.The literature study shows that early introduction of potato onion to Sweden were done by members of the Swedish Garden Association founded in 1832, and in archived protocols potato onion was listed with its French trivial name in the 1830's.However, descriptions from foreign garden literature indicate that the onion called potato onion in France and England differs in qualities from the onions that later came to go by this name in parts of Scandinavia.

Conclusions
The study showed that seed-propagated plant material was spread to Europe from Russia, and from European countries to Sweden during the 19th century and that true seeds and sets of both potato onion and shallots were sold through German seed rms during the 19th century.
The genetic variability of preserved heirloom cultivars of vegetatively propagated multiplying onions might be a result of the increased trade in the 19th century, including true seeds.The rise of the cultivar as a known concept, also for kitchen plants, during the time period re ected in the efforts found in the documentation of the Swedish Garden Association to introduce interesting cultivars and thereby improve the state and the status of the Swedish garden practice at the time.The notion of onions as an ancient crop with qualities connected to different origins are re ected in the early cultivar names, and it is also obvious that new names such as the 'Nordic Shallot', was introduced .
Knowledge of older cultivation systems, introduction history and folk taxonomy deepens the link between the cultural-historical and the biological conservation values of plant material in long time preservation.As earlier described by de Vahl and Svanberg (2022) gene bank accessions may not only be valuable in breeding but also utilized and preserved as part of a biological heritage.With continued focus on utilization of landrace and heirloom cultivars the social values of the plant material may also be strengthened and therefore also need to be de ned further.In a European perspective, documentation on older cultivation systems and culture descriptions could provide further in-depth knowledge of the introduction and distribution paths of shallots.
(Loudon et al. 1840f the publication; Le Bon Jardinier; Almanac pour l'Annee 1840 was reviewed in The gardener's magazine and register of rural & domestic improvement, published in London 1840.The reviewer stated: "E'chalote de Jersey, known in Scotland as the Russian shallot, and E'chalote grosse de M. Houtton are recommended"(Loudon et al. 1840).2.Cultivars, strains and translations.A