Ornithopus L.
Ornithopus is a genus of six species. Five are native in Europe, Macaronesia or the Mediterranean area; an additional species is restricted to South America. Recent molecular studies demonstrated that Mediterranean species form a sister clade with the South American Ornithopus micranthus (Benth.) Arechav. (Visnevschi-Necrasov & al. 2012). One species is native in Belgium, Ornithopus perpusillus L. Ornithopus sativus is sometimes grown as a crop plant (serradella) but only rarely these days.
1. Corolla yellow. Pod laterally compressed, not or hardly constricted between the seeds, with a distinct beak ca. 3-15 mm long === 1. Ornithopus compressus
1. Corolla whitish to pink. Pod terete, much constricted between the seeds (moniliform at maturity), with a short beak ca. 1-3 mm long === 2
2. Corolla 6-10 mm long. Calyx 3,2-5 mm long. Bracts shorter than the inflorescence === 2. O. sativus subsp. sativus
2. Corolla 3,5-4,5 mm long. Calyx 2,3-2,8 mm long. Bracts much longer than the inflorescence (native) === O. perpusillus
Literature:
Ball P.W. (1968) Ornithopus. In: Tutin T.G. & al. (eds.), Flora Europaea, vol. 2. Cambridge University Press, Cambridge: 182.
Degtjareva G.V., Valiejo-Roman C.M., Kramina T.E., Mironov E.M., Samigullin T.H. & Sokoloff D.D. (2003) Taxonomic and phylogenetic relationships between Old World and New World members of the tribe Loteae (Leguminosae): new insights from molecular and morphological data, with special emphasis on Ornithopus. Wulfenia 10: 15-50.
Fu S.M., Hampton J.G. & Hill M.J. (1994) Description and evaluation of serradella (Ornithopus L.) accessions. New Zeal. Journ. Agric. Res. 37(4): 471-479. [available online at: http://www.tandfonline.com/doi/pdf/10.1080/00288233.1994.9513086]
Sell P. & Murrell G. (2009) Flora of Great Britain and Ireland. Vol. 3 Mimosaceae – Lentibulariaceae. Cambridge University Press, Cambridge: XXVIII + 595 p.
Van der Meijden R. (2005) Heukels’ Flora van Nederland (23e druk). Wolters-Noordhoff, Groningen: 685 p.
Visnevschi-Necrasov T., Harris D.J., Faria M.A., Pereira G. & Nunes E. (2012) Phylogeny and genetic diversity within Iberian populations of "Ornithpus L." and "Biserrula L." estimated using ITS DNA sequences. Spanish Journ. Agric. Res. 10(1): 149-154.