Apera Adans.
Apera is a small genus of three species, distributed in Europe and southwestern Asia. One species is native (or probably rather archaeophytic) in Belgium as well: Apera spica-venti (L.) Beauv.
1. Panicle diffuse at maturity, with long patent branches. Leaves up to 10 mm wide (native) === Apera spica-venti
1. Panicle more or less contracted at maturity, with short erect branches. Leaves narrower, usually less than 3 mm wide === 2
2. Upper glume apex acute. Anthers 0,3-0,5 mm long. Callus shortly hairy === A. interrupta
2. Upper glume apex acuminate, shortly awned. Anthers ca. 1,5 mm long. Callus glabrous === A. intermedia
Literature:
Allred K.W. (2007) Apera. In: Barkworth M.E. & al. (eds.), Flora of North America north of Mexico, vol. 24: 788-789. Oxford University Press, New York-Oxford.
Bor N.L. (1968) Gramineae. In: Townsend & al. (eds.), Flora of Iraq, vol. 9. Ministry of Agriculture, Baghdad: VI + 588 p.
Bor N.L. (1970) Gramineae. In: Rechinger K.H. (ed.), Flora of Iran, vol. 70/30. Akademische Druck- und Verlagsanstalt Graz, Austria: 573 p.
Conert H.J. (ed.) (1998) Gustav Hegi Illustrierte Flora von Mitteleuropa. Band I, Teil 3 Poaceae (3.Auflage). Parey Buchverlag, Berlin: XXVII + 898 p.
Davis P.H. (ed.) (1985) Flora of Turkey and the East Aegean Islands, vol. 9. Edinburgh Univ. Press.
Tsvelev N.N. (1984) Grasses of the Soviet Union, part 1 and 2. A.A. Balkema, Rotterdam: XVI + 1196 p.
Tutin T.G. (1980) Apera. In: Tutin T.G. & al. (eds.), Flora Europaea, vol. 5. Cambridge University Press, Cambridge: 172.