1. Onobrychis viciifolia Scop. (Euras.) – A rare, locally naturalised alien. Mostly an escape from or relic of cultivation. Documented in Belgian herbaria since the first half of the 19th century but many early records probably represent cultivated plants. Onobrychis viciifolia was probably introduced around 1550 in our area (Berten & Van Landuyt 2006). In the second half of the 19th century increasingly escaping to suitable habitats (usually dry, calcareous slopes). In 1869 already said to be naturalised in artificial meadows in Korbeek-Lo. Repeated herbarium records in several different locations further suggest local naturalisations around Franchimont (collected between 1925-1980), Magnée (1888-1903), Nismes (1957-1968), Remouchamps (1921-1954), Rochefort (1870-1951), etc. At least in the surroundings of Nismes and Rochefort it still seems firmly established (see http://waarnemingen.be). Most records obviously are from Wallonia (availability of more appropriate habitats?). However, in the past decades Onobrychis viciifolia has probably decreased. In addition to the locations above it was collected after 1950 in, for instance, Bomal (1954), Chenois (1973), Dinant (1973), Dourbes (1955), Fagnolle (1962), Torgny (1960), Villers-en-Fagne (1961) and Wavreille (1971). All these records are from natural but probably slightly disturbed habitats, mainly dry calcareous, sun-exposed slopes (Mesobrometum), sometimes also in abandoned gravel pits. In Flanders Onobrychis viciifolia has always been much rarer. It is best known from an old railway track near Poelkapelle where it persists in small number since many decades (Verloove 2002). Recently, Onobrychis viciifolia is increasingly introduced in newly sown road verges, canal banks, coalmine heaps, etc. usually along with Lotus corniculatus var. sativus, Sanguisorba minor subsp. balearicum, etc. (for instance on coalmine heaps in the surroundings of Charleroi and Mons). It then readily becomes more or less established.
Assessing the exact identity of the Belgian populations of Onobrychis viciifolia requires further study. There are obviously two independent vectors of introduction that probably involve different taxa. According to Sell & Murrell (2009) (see also Clement 2009) the crop plant belongs with subsp. viciifolia (more or less robust plants with erect stems and large corollas). The taxon that is currently included in wild flower seed probably pertains to subsp. decumbens (Jord.) P.D. Sell, a more slender taxon with decumbent to ascending stems and smaller corollas (up to 12 mm long). Plants from wild flower seed mixtures are also often ascribed to Onobrychis sativa Lamk., a taxon that probably merely represents a robust cultivar of O. viciifolia. If more recent herbarium collections from Belgium would become available it would be interesting to study the species’ variability.
Berten B. & Van Landuyt W. (2006) Onobrychis viciifolia. In: Van Landuyt W., Hoste I., Vanhecke L., Van den Bremt P., Vercruysse W. & De Beer D., Atlas van de flora van Vlaanderen en het Brussels gewest. Instituut voor Natuur- en Bosonderzoek, Nationale Plantentuin van België en Flo.Wer: 623-624.
Clement E.J. (2009) Triple trouble over Onobrychis identification. BSBI News 112: 19-20.
Hayot C. (2011) Sainfoin (Onobrychis viciifolia), a forage legume with great potential for sustainable agriculture, an insight on its morphological, agronomical, cytological and genetic characterisation [available online at: https://www.escholar.manchester.ac.uk/api/datastream?publicationPid=uk-ac-man-scw:120238&datastreamId=FULL-TEXT.PDF]
Negri V. & Cenci C.A. (1988) Morphological characterization of natural populations of Onobrychis viciifolia (Leguminosae) from Central Italy. Willdenowia 17(1-2): 19-31.
Sacristan M.D. (1966) Estudios citotaxónomicos sobre el género Onobrychis (L.) Adanson con referencia especial a la citogénetica de al esparceta (O. viciifolia Scop.). An. Estac. Exper. Aula Dei 8: 1-114.
Sell P. & Murrell G. (2009) Flora of Great Britain and Ireland. Vol. 3 Mimosaceae – Lentibulariaceae. Cambridge University Press, Cambridge: XXVIII + 595 p.