Brassica carinata A. Braun (E Afr.) – A very rare and ephemeral alien but possibly overlooked. It was first observed along a former railway line (now cycling track) in Spierre-Helkijn in 2017 (few plants, subsequently confirmed in 2018). Also in 2017 it was seen on the verge of arable land in Ruiselede. This species is now increasingly sown as ‘Ethiopian mustard’ and will probably increase in a near future (as ephemeral alien, naturalization is rather unlikely). B. carinata is also sometimes found (as impurity?) in commercial birdseed mixtures (Stace 2010).
Brassica carinata is derived from B. oleracea x B. nigra. It is similar to the more frequently encountered B. juncea but has leaves with less lobes (often only a large terminal lobe and an additional pair of much smaller lateral lobes), a much shorter beak of the fruit and larger sepals and petals.
This species has been recorded on several occasions in the British Isles and, at one time, was more or less naturalized locally (Stace 2010), although repeated introductions are probably more likely (Clement & Foster 1994). Elsewhere in Europe it is probably often overlooked.
Clement E.J. & Foster M.C. (1994) Alien plants of the British Isles. BSBI, London: XVIII + 590 p.
Rich T. (1987) Cabbage patch - III. B.S.B.I. News 47: 25-26. [available online at: https://archive.bsbi.org.uk/BSBINews47.pdf]
Stace C. (2010) New flora of the British Isles, 3th ed.: XXXII + 1232 p. Cambridge University Press.