Allium paradoxum from Asia to Europe: Ornamental, Invasive, Edible, and Medicinal

An invasive alien plant is a species introduced into a local flora that becomes locally overpopulated and harms its new environment. Invasive plants can have a negative impact on habitats, causing ecological, environmental, or economic damage. They compete for space and nutrients, alter native population densities, and may outcompete native species that consequently are no longer able to fulfil their ecological roles (Ehrenfeld, 2010). Many non-indigenous and now invasive plant species were introduced into Central or Western Europe for reasons ranging from their uses as food to their ornamental value, and many are now naturalized in local flora. For example, in present-day Poland, Ailanthus altissima (Mill.) Swingle, native to China as its common name China sumac suggests, was first used as a decorative tree in parks in 1808; Helianthus tuberosus L. (Jerusalem artichoke) was introduced as a vegetable yielding edible tuber in 1872; the nectariferous plants Echinops sphaerocephalus L. (globe thistle) and Reynoutria japonica Houtt. (Japanese knotweed) arrived in 1809 and 1882 respectively. Some plants introduced for their ornamental or nutritional characteristics are still used today, e.g., Helianthus spp. and Rudbeckia spp. (e.g., Black Eyed Susan, Gloriosa daisy) in parks, Echinocystis lobata (Michx.) Torr. & A.Gray (wild cucumber) and Impatiens glandulifera Royle (Himalayan balsam) in flower gardens, and Cymbalaria muralis G.Gaertn., B.Mey. & Scherb. (Kenilworth ivy) as ground cover in flower beds and urban gardens (Tokarska-Guzik et al., 2012). Such introduced species can spread independently in suitable habitats and with adapted modes of dispersal or as a consequence of human activities, especially if they become fashionable or otherwise desirable, and thereby become invasive. Allium paradoxum (M. Bieb.) G. Don (few-flowered garlic, few-flowered leek, paradoxical onion, or Asian wild onion) was first described by Marshall von Bieberstein (1819) and is native to northern Iran (Khodadadi et al., 2015), Georgia (Akhalkatsi et al., 2008), Azerbaijan (the Talysh Mountains) (Rukšāns, 2007), Armenia (Fayvush et al., 2017), and southernmost Russia: it grows in the wild in the Northern Caucasus, in the federal republics of Chechnya, Dagestan, and North Ossetia-Alania (Radzhi et al., 2008). It has also been reported as wild in north-eastern Iraq (Pieroni et al., 2017, 2019). I present the history of A. paradoxum since its introduction as an ornamental in Central Europe and the chronology of its spread from house gardens to public and private parks and wild areas. Wild food foragers and gardening enthusiasts are now sharing their observations on A. paradoxum on the Internet. Here I address the trajectory of this species, which is conspicuous with its vivid green leaves in April, when most perennials are still dormant, from its introduction as a food and medicinal plant to its impact on the native flora, and its current distribution across Central Europe (Fig. 1).


Introduction
An invasive alien plant is a species introduced into a local flora that becomes locally overpopulated and harms its new environment. Invasive plants can have a negative impact on habitats, causing ecological, environmental, or economic damage. They compete for space and nutrients, alter native population densities, and may outcompete native species that consequently are no longer able to fulfil their ecological roles (Ehrenfeld, 2010).
Many non-indigenous and now invasive plant species were introduced into Central or Western Europe for reasons ranging from their uses as food to their ornamental value, and many are now naturalized in local flora. For example, in present-day Poland, Ailanthus altissima (Mill.) Swingle, native to China as its common name China sumac suggests, was first used as a decorative tree in parks in 1808; Helianthus tuberosus L. (Jerusalem artichoke) was introduced as a vegetable yielding edible tuber in 1872; the nectariferous plants Echinops sphaerocephalus L. (globe thistle) and Reynoutria japonica Houtt. (Japanese knotweed) arrived in 1809 and 1882 respectively. Some plants introduced for their ornamental or nutritional characteristics are still used today, e.g., Helianthus spp. and Rudbeckia spp. (e.g., Black Eyed Susan, Gloriosa daisy) in parks, Echinocystis lobata (Michx.) Torr. & A.Gray (wild cucumber) and Impatiens glandulifera Royle (Himalayan balsam) in flower gardens, and Cymbalaria muralis G.Gaertn., B.Mey. & Scherb.
(Kenilworth ivy) as ground cover in flower beds and urban gardens (Tokarska-Guzik et al., 2012). Such introduced species can spread independently in suitable habitats and with adapted modes of dispersal or as a consequence of human activities, especially if they become fashionable or otherwise desirable, and thereby become invasive.
Allium paradoxum (M. Bieb.) G. Don (few-flowered garlic, few-flowered leek, paradoxical onion, or Asian wild onion) was first described by Marshall von Bieberstein (1819) and is native to northern Iran (Khodadadi et al., 2015), Georgia (Akhalkatsi et al., 2008), Azerbaijan (the Talysh Mountains) (Rukšāns, 2007), Armenia (Fayvush et al., 2017), and southernmost Russia: it grows in the wild in the Northern Caucasus, in the federal republics of Chechnya, Dagestan, and North Ossetia-Alania (Radzhi et al., 2008). It has also been reported as wild in north-eastern Iraq (Pieroni et al., 2017. I present the history of A. paradoxum since its introduction as an ornamental in Central Europe and the chronology of its spread from house gardens to public and private parks and wild areas. Wild food foragers and gardening enthusiasts are now sharing their observations on A. paradoxum on the Internet. Here I address the trajectory of this species, which is conspicuous with its vivid green leaves in April, when most perennials are still dormant, from its introduction as a food and medicinal plant to its impact on the native flora, and its current distribution across Central Europe (Fig. 1).

Methods
To ascertain the range of A. paradoxum in the flora of Europe I consulted published botanical data (1819-2022), as well as online floristic databases maintained by research or nature conservation institutions. 1 Since Czechia (The Czech Republic), Belgium, and Poland do not have country-level databases, or they were out-of-date, I collected or supplemented relevant data from appropriate floristic publications. I plotted these data on a map to present the general distribution. The floristic data provided by online databases may have been collected according to non-uniform methods, depending on the country and period. Dates of floristic finds are noted in scientific articles, usually for the earliest occurrence of the species. In databases, dates are reduced to arbitrarily established periods. The character of the sites (cultivated vs. wild) of A. paradoxum has been cited here from publications, but it was not represented in cartograms at country level. Such information, if it exists, should be sought from the original datasets held by relevant institutions.
To assess use of the plant as a current source of wild food, I browsed posts and information published in modern wildfood, gardening, and cuisine blogs, vlogs, and web stores, using popular search engines provided by Google, YouTube, and Facebook. I retrieved pharmacological and ethnopharmacological data on A. paradoxum using the following platforms: ScienceDirect, Jstor, PubMed, Springer, and Wiley.
In 1979, the first four localities in the Netherlands in which A. paradoxum were reported were: "in some woodlets on the inner side of the dunes near Heemstede En Bloemendaal (Noord-Holl region)" (Weeda, 1979). The floristic database for the Netherlands (Floron, 2020) holds 102 identifications of this species for the years 1990-2020. In Belgium, the first A. paradoxum was discovered in 1989 and a second had been identified by 2000 (Meerts, 2000). It was also found in Vienna In 1971 (Forstner & Hübl, 1971), and Salzburg in 1984 (Wittmann, 1984). Today, it grows in single localities in Denmark (Naturbasen, 2001) and is distributed in most lowland provinces of Germany (104 localities as of 2021) (Flora Web, 2022). It has several localities in eastern Ireland (OABIF, 2022), too. In Switzerland, the number of its localities has increased from five (before 1992) to 26 (InfoFlora, 2021).

Current Status of Allium paradoxum in Western and Central Europe
A. paradoxum was classified as an invasive species in the British Isles in The Wildlife and Countryside Act (1981). After 2010, it was awarded the same category in Germany (Nehring et al., 2013) and Belgium (Graulich, 2017). In 2012, A. paradoxum was still rare enough to be classified as an ephemerophyte in Central Europe (Tokarska-Guzik et al., 2012), but its detailed status in various countries soon became diverged. Notably, in the Czech Republic it is already naturalized (Pyšek et al., 2012) and considered "locally very invasive," particularly in Prague (Lustyk & Doležal, 2018), but was apparently absent in Slovakia in 2012 (Medvecká et al., 2012).

Habitats
In Britain, Allium paradoxum occupies riverbanks, roadsides, field margins, rough and waste ground, and deciduous woodlands. It is very invasive in disturbed habitats and is increasingly abundant throughout its range, especially in southern Scotland (Flora Web, 2022). In Poland, A. paradoxum habitats include riparian forests on small streams (Smoczyk, 2010), large old parks (Rostański, 1961), fertile deciduous forests (Bacieczko & Wołejko, 2011), and old village cemeteries (Sobisz & Antkowiak, 2009). In the Czech Republic, it was reported in similar habitats, namely, abandoned city parks in Prague (Kopecký & Hejný, 1971) and Brno (Krahulec, 2002;Kubešová, 2000). There were more than 20 such localities across the country (Krahulec & Duhoslav, 2019). In Hungary, it colonized an abandoned park in Budapest Tétény where doubled in area from two m 2 to four m 2 within a year (Korda, 2013). In Latvia, it grew in disturbed forest and shrub-land habitats in Riga along the Daugava River (Evarts-Bunders & Bojāre, 2020). Carpet-like populations in parks or forests, as well as in gardens, can consist of 420 flowering specimens per one m 2 (Fabiszewski & Brej, 2007).
Urban parks currently appear to offer the most favorable habitats for the persistence and expansion of A. paradoxum populations. Wild food enthusiasts in Poland report localities of A. paradoxum in parks in Wrocław, Warsaw, Elbląg, and Kraków (Łuczaj, 2019). In Germany, it is common in parks and forests of Berlin: Pankow Blankenfelde, Krumme Lanke (Böttcher, 2021). Park visitors in Berlin were generally familiar with A. paradoxum as a wild food in 2014 (Palliwoda et al., 2017). For these countries, amateur reports on this plant are more informative than findings published in floristic articles.

Taxonomy and Dissemination Biology
Allium paradoxum dissemination and diaspore dispersal are twofold: the dominating diaspore type can be either inflorescence bulbils accompanied by very few flowers, or only flowers producing fruits with seeds. This difference became the basis for the division of this species into two infraspecific taxa: Allium paradoxum var. paradoxum produces numerous inflorescence bulbils at the base of each umbel and only 2, 1, or 0 flowers per umbel (Stearn, 1987). On average, there are 14 such bulbils per one stem (Fabiszewski & Brej, 2007). This variety is common in Europe. Inflorescences 1 3 are variable: primary umbels can hold either several bulbils only, or the bulbils can be accompanied by 1-2 pedicellate flowers. A primary umbel can also produce 1 to 4 proliferations, each capped with a secondary or tertiary umbel consisting of flowers or bulbils (Brennenstuhl, 2015). Seeds are rare and may not be viable (ISNI, 2021). Barling (1971) in an extensive search within the Gloucestershire population found only five mature seeds in a sample of 250 plants.
The inflorescence bulbils of var. paradoxum fall after flowering (which ends in May). The plant can also spread vegetatively by sister bulbs which grow from the base of the main bulb in the soil.
A. paradoxum var. normale Stearn produces 3-5 flowers per inflorescence (Korda, 2013) and does not form inflorescence bulbils. This variety was described only in 1987 (Stearn, 1987), so older publications do not mention it. It was first reported from the species' native range (the Talysh Mountains in Armenia) in 1987 (Rukšāns, 2007). In Europe, it was reported by Dubovik et al. (2017), but their text was not clear enough to conclude that it had been found in Belarus. Korda (2013) found var. normale in Budapest. In 2012, Danihelka et al. (2012) listed it in the Czech Republic but only as a garden plant. A cultivar named Allium paradoxum 'Talish' which represents var. normale was offered as a garden plant in Europe in Latvia (Rukšāns, 2007). Stearn (1987) published the following speculation on garlic species that can produce inflorescence bulbils: "… under man-made or man-influenced conditions, especially in gardens, the bulbilliferous [i.e., bulbil-bearing] form may survive better than the normal one and, through an inadvertent or deliberate introduction, may extend far beyond the natural range of the parent species.
[…] Hence some species of Allium have first come to the notice of botanists in a bulbil-bearing form which has accordingly become the nomenclatural type of a specific name." He listed A. paradoxum among 10 species of Allium best (or first) known as bulbil-bearing forms.

Few-Flowered Garlic as an Edible Plant
Iran A. paradoxum is widely known as a food plant in northern Iran, where it is native (Khodadadi et al., 2015). In the same region, it is grown in home gardens as a cultivated vegetable and spice, especially in Mazandaran province (Abbasi et al., 2008). Young leaves and infructescences are used raw as seasoning, boiled or fried, and pickled in vinegar (Pieroni et al., 2018). Other authors noted: "Leaves and bulbs are used as a fresh vegetable; widely collected and sold at markets in many towns in northern Iran. This species is endangered because of over-harvesting from the wild" (Nabavi et al., 2012a, b).

Iraq
In north-eastern Kurdish Iraq, leaves of A. paradoxum are consumed raw as sawza; as bread and yogurt seasoning, cooked with rice or bulgur, and preserved in brine (lactofermented) . In south-eastern Iraqi Kurdistan (Hawraman area) they are boiled in soup or wrapped in dough and fried (Pieroni et al., 2017).

Armenia and Azerbaijan
Young leaves, stems, and bulbs of Allium paradoxum in fresh or pickled form are used as a seasoning for various Armenian dishes (Fayvush et al., 2017). The leaves are used as a snack, as cheese seasoning, fried, cooked in soup, pickled and fermented in brine (Pieroni et al., 2018). In Azerbaijan, leaves and stems with bulbs are among the ingredients of national dishes: dovga (a soup of yogurt, various greens, rice, and eggs), kutab (various edible greens baked in a thinly rolled dough), and kuku (an omelet with various greens, sometimes with added meat or fish, and often mixed with yoghurt) (Fayvush et al., 2017). The leaves are also a snack .

Europe
Enthusiasts of wild edible plants call themselves foragers and what they collect is "wild food" (Williams, 2015). I gathered opinions on the value of A. paradoxum published in contemporary Internet resources such as cuisine blogs, and wild food foraging blogs, and videos.

Parts Used and their Taste
Bulbils taste of garlic and chives (LadyKitchen, 2020). Flowers are sweet and tasty (AuJardin, 2021). Leaves are slightly sweet, and more delicate than the bulb; mature plants have a stronger taste (AuJardin, 2021). "Bulbils are not as strong in taste as garlic (Allium sativum L.)" (Wild Food UK, 2019). "The bulbils […] bring some almost melon-like mellowness to their allium pungency" (Williams, 2015). They can be harvested when the plant has finished its vegetal cycle and dried (AuJardin, 2021). A German cuisine blogger Haupt (2017) wrote that A. paradoxum: "… tastes a little less intense than the real wild garlic [i.e., A. ursinum L.]. That's why it's a great alternative for those who don't like or can't stand the very intense taste of garlic."

Usage
A Scottish food blogger Bird (2016) posted recipes for pesto made from several species of wild edible garlic species available in Britain: three-cornered leek (Allium triquetrum L.), ramsons (A. ursinum L.), rosy garlic (A. roseum L.), and A. paradoxum. She found the value of these species to be comparable. The herb became an ingredient in pesto, cleansing drinks, spreads, salads, salad dressings, steak tartare, and sandwiches (Vlkova, 2021). Another blogger proposed making garlic butter, garlic oil (by digesting the herb in olive oil), and garlic quark (soft white cheese). The herb can be also pickled or cooked as spinach (Wild Food UK, 2019). Inflorescence bulbils are dried and used as a condiment (AuJardin, 2021).

Remarks on Propagation and Cultivation by Amateurs
Two quotations from the Polish Internet published between 2014 and 2015 deserve our attention: 1) "While Allium paradoxum propagates easily, there are still no farmers who would undertake the cultivation of this crop for food" (Zarówna, 2014). 2) "Controlled (!) sites are increasing in number […] as a result of the activities of [a non-profit] ecological group Chwastożercy ("Weedvores" analogous with "herbivores"). They disseminate this plant in Poland to attract more attention from consumers to it. A. paradoxum bulbils are offered to participants of some "Weedvores" group events. Botanists have already recognized it as invasive, although it is still relatively rare in Poland" (Rumińska, 2015). Between 2015 and 2019, enthusiasts promoted the consumption of A. paradoxum by organizing so-called wild food events (workshops and excursions) in parks of Wrocław (SW Poland). On their fan page, The meetings were announced on the internet: "Participants will receive a gift, i.e., seedlings from our garden -a bunch of paradoxical garlic to plant in one's own garden." In their older posts they draw attention to saving the rare native food plant Allium ursinum L.: " [Foragers] are increasingly exploiting the populations of protected A. ursinum in a destructive manner" (Chwastożercy, 2017). A German forager Schatz (2009) wrote: "Allium ursinum is rare in our region, but […] we are blessed with a similarly tasting plant […] Allium paradoxum […] Here, the herb is somewhat of a nuisance for native plants, as it spreads over large areas. So, you do not have to hesitate to harvest it (unlike A. ursinum, which is already on the list of endangered species in some regions of Germany)." And finally, one German and one Latvian gardening portal offered A. paradoxum for sale in 2021.

Modern Vernacular Names of A. paradoxum
An insight into the modern vernacular names of a popular plant can reveal attitudes towards it. German names for A. paradoxum include Wunderlauch ("wonderful garlic"), Seltsamer Lauch ("strange garlic"), and Berliner Bärlauch. While the first two are literal translations of its Latin binomial, the latter means "bears' garlic of Berlin" and appeared on the Internet only 10 years ago. It reveals two pieces of ethnobotanical information: 1) A. paradoxum became an equivalent of a less common wild edible garlic, Allium ursinum L. (the Latin binomial of which means "bears' garlic"), and 2) A. paradoxum is common in and known from parks and forests in and around Berlin. Such a distribution and abundance are confirmable in both the Flora Web (2022) database and on the German Internet. A. ursinum as a garden plant was described by Jäger (1866), but its cultivation is from seeds or sister bulbs, so the ease of growing A. paradoxum seems attractive to people who had difficulty growing A. ursinum.

Medicinal Properties
The medicinal properties of A. paradoxum as well as its ethnopharmacological uses were studied only in the twentieth century. In Iran, it was recorded as an antiacne and digestive folk remedy (Mozaffarian, 2012), and the following pharmacological effects have been confirmed experimentally: antihaemolytic (Ebrahimzadeh et al., 2010), antioxidant (Khodadadi et al., 2015;Mohammadi-Motamed & Naghibi, 2010), protective against induced nephrotoxicity in mice (Dehghan et al., 2016;Nabavi et al., 2012a, b), as well as antimalarial (Elmi et al., 2021). Phenolic compounds were identified in bulbs as substances inducing an anti-inflammatory effect (Ghavam-Haghi & Dinani, 2017). Regardless of this research, A. paradoxum is beginning to be recognised in Europe as a folk medicinal plant,. first suggested published by an Iranian author Khoshbakht (2006: 20), i.e., before any pharmacological research was published on the topic. He wrote: "Although no specific mention of medicinal uses has been seen for this species, members of this genus are, in general, healthy additions to the diet. They contain sulfur compounds (which give them their onion flavour) and when added to the diet on a regular basis they help reduce blood cholesterol levels, act as a tonic to the digestive system and tonify the circulatory system." This transfer of knowledge from other known medicinal garlic species to A. paradoxum, based on similarity in taste and scent, can be done independently in any part of the world and repeats the reasoning about A. paradoxum as a food plant. This quotation from Khoshbakht (2006) has been widely taken up on the Internet, e.g., by Plants for a Future (2010), Németh (2022), Natural Medicinal Herbs (2022, and makes A. paradoxum a candidate for a folk medicinal plant in Europe. The history of folk medicinal plants records a similar case of Reynoutria japonica, introduced in Europe in the second half of the nineteenth century, now very invasive, which became used in folk medicine in Germany as early as the 1920s (its stems are similar to rhubarb and therefore were used as a substitute for it) (Krober, 1929). However, the history of A. paradoxum in Europe is quite different from another Allium genus, A. ramosum L., which has been recently reported as newly identified in North-Eastern Poland and East European Russia but is still very rare. A ramosum was introduced to Europe as a spice in the last decades of the twentieth century and is readily available to gardeners (Seregin & Korniak, 2013).  Stearn's (1987) speculation on the ability of bulbil-bearing garlic to expand in man-made or man-influenced habitats proved to be correct for Allium paradoxum, which, in addition, has recently appealed to and is being deliberately spread by wild-food foragers and growers; 6. The range and frequency of Allium paradoxum in central Europe are underestimated. Activities of wild food enthusiasts increase the spread of its diaspores. Any intentional spread of this plant in natural and semi-natural ecosystems (e.g., parks) should be banned. Planting or or transplanting it (into gardens and parks) can accelerate its invasiveness. 7. The status of A. paradoxum across Europe remains paradoxical. It outcompetes native plants (in Britain, Germany, and Czechia) and gardeners complain that it is a hard to manage weed (in Scotland). At the same time, it is promoted by amateurs as an attractive source of wild food, both harvested in the wild and cultivated (in Germany, Poland, the Czech Republic). 8. Modern European cuisine uses A. paradoxum in similar ways as in the Caucasus region where it is native), and in both regions it is both foraged from wild stands and grown in gardens. The medicinal value of A. paradoxum in self-healing, in Europe inspired by garlic or chives (amateur phytotherapy) seems to be a minor and recent justification for growing this plant.

Conclusions
Author contributions J.D. wrote the entire manuscript text and drew the Fig. 1

Competing Interests
The authors declare no competing interests.

Informed Consent
The nature of this research did not require informed consent.

Conflict of Interest
The author declares no potential conflict of interest.
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http:// creat iveco mmons. org/ licen ses/ by/4. 0/.