1. Piptatherum miliaceum (L.) Coss. (syn.: Oryzopsis miliacea (L.) Benth. et Hook. ex Aschers. et Schweinf.) (Medit.) – A very rare alien. Formerly exceptionally recorded as an ephemeral wool alien in the valley of river Vesdre (Lambinon 1993). In the past decades more regularly observed, mostly in urban areas and probably always associated with either birdseed or the horticultural trade (the species is a frequent weed in nurseries). Seen for instance in Antwerpen in 1993 and 1994 (as pavement weed, probably from birdseed; see Verloove & Vandenberghe 1997)) and in Gent (alley) since 2004 (confirmed, for instance, in 2014). In 2011 also recorded as a grain alien on an unloading quay for cereals in the port of Antwerpen. Piptatherum miliaceum also is a rather frequent weed in plant containers in plant nurseries (especially those with Olea and other ornamental plants from the Mediterranean area) (Hoste & al. 2009). A more or less established population with 15-20 individuals was observed as a pavement weed in Vilvoorde in 2018.
The Belgian collections can be ascribed to two more or less distinct races that have been accepted at various taxonomic ranks. Present-day authors seem to elevate both to species rank (see for instance Romaschenko & al. 2011). They are here accepted as subspecies: subsp. miliaceum (syn.: Oryzopsis multiflora (Cav.) Druce) and subsp. thomasii (Duby) Freitag (syn.: P. thomasii (Duby) Kunth, Oryzopsis miliacea var. thomasii (Duby) Boiss.). They are separated as follows:
- Lowermost inflorescence branches verticillate with usually 4-8 (rarely up to 20 branches), all bearing spikelets === subsp. miliaceum
- Lowermost inflorescence branches verticillate with 20-50 short, usually sterile branches (rarely some branches with one spikelet) === subsp. thomasii
Subsp. miliaceum is by far the least rare these days.
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Herbarium specimen subsp. miliaceum
Herbarium specimen subsp. thomasii
Literature:
Hoste I., Verloove F., Nagels C., Andriessen L. & Lambinon J. (2009) De adventievenflora van in België ingevoerde mediterrane containerplanten. Dumortiera 97: 1-16.
Lambinon J. (1993) Quelques données inédites sur des graminées adventices ou subspontanées en Belgique. Belg. Journ. Bot. 126: 3-12.
Romaschenko K., Peterson P.M., Soreng R.J., Futorna O. & Susanna A. (2011) Phylogenetics of Piptatherum s.l. (Poaceae: Stipeae): evidence for a new genus, Piptatheropsis, and resurrection of Patis. Taxon 60(6): 1703-1716.
Verloove F. & Vandenberghe C. (1997) Nieuwe en interessante voederadventieven in België en aangrenzend Nederland, hoofdzakelijk in 1996. Dumortiera 68: 13-26.