Bromus catharticus

Bromus catharticus Vahl (syn.: B. schraderi Kunth, B. unioloides (Willd.) Beauv., B. willdenowii Kunth, Ceratochloa cathartica (Vahl) Herter, C. unioloides (Willd.) Beauv. ) (S-Am.) – A rather regular alien, known at least since 1864 (without further details). Chiefly introduced with cereals, formerly also a wool alien. Furthermore intentionally introduced as a fodder grass. Often very persistent and perhaps locally becoming naturalised in some (sub-) urban areas, especially around Antwerpen and Gent. However, recently also recorded in the valley of river Meuse in much more natural habitats (Duvigneaud & Saintenoy-Simon 1996).

Bromus catharticus, especially forms with unusually long awns, is regularly confused with B. carinatus. In addition to the characters provided in the key, in Bromus catharticus spikelets are often more strongly laterally compressed (flattened), often strikingly bicoloured and lemmas and glumes more-veined.

Bromus catharticus itself also is a variable species. Kloos (1918) thoroughly investigated the variability of Dutch collections. Bromus catharticus is now widely accepted as a collective taxon that includes, among others, B. brevis. The latter was formerly recorded as wool alien in the Vesdre valley. It chiefly differs in awn-length and is, indeed, perhaps better treated as a mere variant of Bromus catharticus (var. rupestris), characterised by awns 0,3-0,5 (-1) mm long and folded young leaf blades whereas var. catharticus has awns 0,5-4 (-5) mm long and convolute young leaf blades (Peterson & Planchuelo 1998). It is still encountered nowadays in Europe (see for instance Ryves & al. 1996) and should be looked for in Belgium as well.

The nomenclature and taxonomy of Bromus catharticus have long been controversial. Some recent authors still adopt Bromus unioloides (syn.: B. willdenowii) as the correct name for this species, while B. catharticus, at least in part, represents a distinct species (see Ammann 2007).

Herbarium specimen 1

Herbarium specimen 2

Bromus catharticus, Mortsel (Wilrijk), former railway track, November 2011, L. Janssen Bromus catharticus, Harelbeke, former railway track, September 2011, D. Derdeyn
 Bromus catharticus, Harelbeke, former railway track, September 2011, D. Derdeyn  Bromus catharticus, Harelbeke, former railway track, September 2011, D. Derdeyn

Bromus catharticus, spikelet


Selected literature:

Ammann K. (2007) Die Gattung Bromus in Südwest- Mittel- und Zentraleuropa [available online at: and].

Duvigneaud J. & Saintenoy-Simon J. (1996) Bromus catharticus dans la vallée mosane. Adoxa 10: 7-8.

Ekman J. (1989) Sloklosta Bromus sitchensis och plattlosta B. willdenowii i Sverige. Svensk Bot. Tidskr. 83: 87-100.

Hamzehee B., Alemi M., Attar F. & Ghahreman A. (2007) Bromus catharticus and Bromus danthoniae var. uniaristatus (Poaceae), two new records from Iran. Iranian J. Bot. 13(1): 33-36.

Kloos A.W. (1918) Poging tot een systematische indeeling van de vormen van Bromus uniolides (Willd.) H.B.K. die in Nederland waargenomen zijn. Nederl. Kruidk. Arch. 1917: 157-180.

Peterson P.M. & Planchuelo A.M. (1998) Bromus catharticus in South America (Poaceae: Bromeae). Novon 8: 53-60.

Pinto Escobar P. (1976) Nota sobre el ejemplar tipo de "Bromus catharticus" Vahl. Caldasia 11(54): 9-16.

Planchuelo A.M. (1991) Estudios sobre el complejo Bromus catharticus (Poaceae): 1. Evaluación estadística de los caracteres taxonómicos. Kurtziana 21: 243-257.

Planchuelo A.M. (2006) A new combination in the Bromus catharticus complex (Poaceae: Bromeae sect. Ceratochloa). Sida 22: 555-560.

Ryves T.B., Clement E.J. & Foster M.C. (1996) Alien grasses of the British Isles. BSBI, London: XX + 181 p.

Schneider M. & Vegetti A. (1996) Tipologia de las inflorescencias en Bromus catharticus y Bromus auleticus (Poaceae). Parodiana 9(1-2): 159-163.

Simon B.K. (1982) Nomenclatural notes on Bromus catharticus Vahl. Austral. Syst. Bot. Soc. Newsl. 33: 12-13.

Vegetti A.C. (1997) Formas de crecimiento en Bromus catharticus y B. auleticus (Poaceae). Kurtziana 25: 165-182.

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith