Polypogon Desf.
(incl. Chaetotropis Kunth)
Polypogon, as currently circumscribed (i.e. including Chaetotropis), is a relatively small genus of ca. 18 species. Most are confined to warm-temperate to tropical regions of the world. None is native in Belgium. The exact placement of Polypogon viridis is still controversial. According to Jacobs (2009) it lacks some essential features of Polypogon (e.g. the terminally-awned glumes). Moreover, it shares the characteristic lemma surface of Agrostis s.str. He therefore maintains Polypogon viridis in Agrostis, the genus where it was originally described by Gouan (as A. viridis Gouan). Pending future molecular studies, it is here accepted as a species of Polypogon (see also Euro+Med Plantbase).
xAgropogon lutosus (Poir.) P. Fourn. (syn.: xA. littoralis (Smith) C.E. Hubbard), an intergeneric hybrid involving Agrostis stolonifera and Polypogon monspeliensis (cf. Rúgolo de Agrasar & Molina 1997), has been reported from Belgium (Lambinon & al. 2004). This reference, however, from a sand-raised site in Diest, in fact belongs to the North American grass seed alien Agrostis exarata Trin. (Verloove & Lambinon 2008). In 2015 this hybrid was discovered, apparently for the first time in Belgium, in the Antwerp port area in Kallo.
1 Perennial grasses. Glumes and lemmas unawned (or exceptionally the lower glume with a short awn) === 3. Polypogon viridis
1 Annual grasses. Glumes awned, awn 3,5-12 mm long. Lemmas awned (but soon caducous!) or unawned === 2
2 Glumes tuberculate at base (covered with short stout spinules), awn inserted at ca. ¼ from apex (glume deeply bifid at apex). Lemmas awnless === 1. P. maritimus
2 Glumes not or much less tuberculate at base, awn subapical. Lemma awned (but soon caducous!) === 2. P. monspeliensis
Additional aliens: Polypogon chilensis (Kunth) Pilger (syn.: Chaetotropis chilensis Kunth) (S-Am., wool alien), P. elongatus Humb., Bonpl. et Kunth [syn.: Chaetotropis elongata (Humb., Bonpl. et Kunth) Björkman] (Am., wool alien), Polypogon fugax Nees ex Steud. (syn.: P. demissus Steud.) (Medit., wool and grain alien) and Polypogon rioplatensis Herter [syn.: Chaetotropis rioplatensis (Herter) Björkman] (S-Am., wool alien).
Literature:
Auquier P. (1978) Graminées adventices nouvelles ou intéressantes pour la flore belge, I. Bull. Soc. Roy. Bot. Belg. 111: 151-163.
Barkworth M.E. (2007) Polypogon. In: Barkworth M.E. & al. (eds.), Flora of North America north of Mexico, vol. 24: 662-668. 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.
Conert H.J. (ed.) (1998) Gustav Hegi Illustrierte Flora von Mitteleuropa. Band I, Teil 3 Poaceae (3.Auflage). Parey Buchverlag, Berlin: XXVII + 898 p.
Finot V.L., Contreras L., Ulloa W., Marticorena A., Baeza C.M. & Ruiz E. (2013) El género Polypogon (Poaceae: Agrostidinae) en Chile. J. Bot. Res. Inst. Texas 7(1): 169-194. [available online at: http://brit.org/webfm_send/356]
Jacobs S.W.L. (2009) Agrostis. In: Wilson A. (ed.), Flora of Australia 44A (Poaceae 2). CSIRO Publishing, Melbourne: 163-173.
Jansen P. (1951) Flora Neerlandica, deel 1, aflevering 2. KNBV, Amsterdam: 272 p.
Lambinon J., Delvosalle L., Duvigneaud J. (avec coll. Geerinck D., Lebeau J., Schumacker R. & Vannerom H. (2004) Nouvelle Flore de la Belgique, du Grand-Duché de Luxembourg, du Nord de la France et des Régions voisines (Ptéridophytes et Spermatophytes). Cinquième édition. Jardin botanique national de Belgique, Meise: CXXX + 1167 p.
Rúgolo de Agrasar Z.E. & Molina A.M. (1997) Presencia del híbrido xAgropogon littoralis (Gramineae: Agrostideae) en Chile. Hickenia 11: 209-214.
Ryves T.B., Clement E.J. & Foster M.C. (1996) Alien grasses of the British Isles. BSBI, London: XX + 181 p.
Verloove F. & Lambinon J. (2008) Neophytes in Belgium: corrections and adjustments. Syst. Geogr. Pl. 78: 63-79.