3. Digitaria sanguinalis (L.) Scop. (Medit., As.) – A very common, more or less widely naturalized alien (see recent distribution map for Flanders in Hoste 2006), known in Belgium at least since 1803. Formerly introduced with wool, grain,… and now naturalized in various habitats but mostly as an agricultural weed in (maize) fields. Less frequently established in ports, urban areas, etc.
Two more or less distinct subspecies have been recorded in Belgium (see key below). Subspecies sanguinalis is by far the commonest taxon (and possibly the only one that is genuinely naturalized). However, subspecies pectiniformis Henrard is perhaps often overlooked. It persists since quite some time in relative abundance and in several localities on gravelly soil near railway stations in Brugge. In identical circumstances it was also recorded in 2013 in Mons (Arsenal). A herbarium revision yielded several old as well as more recent records. Old floras erroneously referred to it as Digitaria sanguinalis var. ciliaris (Retz.) Parl. (see for instance Durand 1899). The distinction between these subspecies is not always straightforward and their taxonomic value probably is restricted. Typical plants may be distinguished as follows:
Margins of lower lemma at maturity with long, glassy, more or less divergent bristles emerging from crateriform protrusions === subsp. pectiniformis
Margins of lower lemma variably hairy or glabrous, never with long glassy bristles === subsp. sanguinalis
Several closely related taxa are common weeds in many warm-temperate areas. They are often very similar to Digitaria sanguinalis and might have been overlooked: Digitaria bicornis, D. horizontalis Willd., D. nuda Schumach, etc. (see for instance Wipff 2003 or Wilhalm 2009 for the separation of some of these species).
 |
|
|
 |
 |
|
|
|
Selected literature:
Durand Th. (1899) Prodrome de la flore belge. Tome III Phanérogames. Editions A. Castaigne, Bruxelles: 1112 p.
Hoste I. (2006) Digitaria sanguinalis. 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: 341-342.
Kocián P. (2010) Notes on the distribution of Digitaria sanguinalis subsp. pectiniformis on the railways in northern Moravia and Silesia (Czech Republic) (in Czech). Acta Mus. Beskid. 2: 7-14. [available online at: http://www.kvetenacr.cz/publikace/Kocian-2010-Digitaria-sanguinalis-pectiniformis.pdf]
Robbrecht E. (1983) Autosnelwegneofieten, een kategorie van graanadventieven in opkomst? Dumortiera 26: 6-13.
Verloove F. (2002) Ingeburgerde plantensoorten in Vlaanderen. Mededeling van het Instituut voor Natuurbehoud n° 20: 227 p.
Webster R.D. & Hatch S.L. (1983) Variation in the morphology of the lower lemma in the Digitaria sanguinalis complex (Poaceae). Iselya 2(2): 3-13.
Wilhalm T. (2009) Digitaria ciliaris in Europe. Willdenowia 39: 247-259.
Wipff J.K. (2003) Digitaria. In: Barkworth M.E. & al. (eds.), Flora of North America north of Mexico, vol. 25. Oxford University Press, New York-Oxford: 358-383.