Crambe abyssinica Hochst. ex R.E. Fries (syn.: C. hispanica L. subsp. abyssinica (Hochst. ex R.E. Fries) A. Prina) (trop. Afr.) – A very rare and ephemeral alien. Recorded in abundance (several hundreds) as a road verge casual along N37 between Pittem and Deinze in 1994 (still few specimens present in 1995 but gone by 1996) (Verloove & Vandenberghe 1995), doubtlessly from spilled seeds. Similar recent records are available from several different neighbouring countries (the British Isles, the Netherlands). In 2016 also seen in the city of Antwerp, without obvious vector of introduction.
Crambe abyssinica is sometimes grown as a commercial oilseed crop but probably not so in Belgium.
Crambe abyssinica superficially looks like the rare native species Calepina irregularis (Asso) Thell. However, Calepina is glabrous and has reticulate-veined siliculae without a lower segment. In Crambe, on the contrary, siliculae have a stalk-like lower segment and a smooth, globose upper segment.
Crambe abyssinica and C. hispanica are very similar and have long been confused. Belgian collections found in the 1990's are characteristic in having the upper part of the fruit slightly 4-ribbed (see Prina 2000), a feature of C. abyssinica. The plants found in Antwerp in 2016, however, seem to have terete fruits which would suggest C. hispanica s.str. Recent records from Austria apparently also belong to genuine C. hispanica (Bernhardt & Laubhann 2006).
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References
Bernhardt K.G. & Laubhann D. (2006) Crambe hispanica, der Spanische Meerkohl (Brassicaceae) als Kulturbegleiter. Neilreichia 4: 121-124.
Braithwaite M. (2007) Abyssinian Mustard, a naturalised crop? BSBI News 104: 36-37.
Jonsell B. (1976) Some tropical African Cruciferae. Bot. Notiser 129(2): 123-130.
Lessman K.J. (1975) Variation in Crambe: Crambe abyssinica Hochst. J. Amer. Oil Chem. Soc. 52(9): 386-389.
McKean D.R. (2006) Abyssinian Mustard, a relatively new crop in Britain. BSBI News 101: 35.
Melzer H. & Barta T. (2000) Crambe hispanica, der Spanische Meerkohl, ein Neufund für Österreich, und weitere floristische Neuigkeiten aus Wien, Niederösterreich und dem Burgenland. Linzer Biologische Beiträge 32(1): 341-362.
Prina A. (2000) A taxonomic revision of Crambe, sect. Leptocrambe (Brassicaceae). Bot. J. Linn. Soc. 133(4): 509-524.
Seegeler C.J.P. (1983) Oil plants in Ethiopia, their taxonomy and agricultural significance. Addis Ababa, College of Agriculture and Wageningen, Agricultural University: 368p.
Smejkal M. (1989) Crambe abyssinica v Ceskoslovensku. Zpr. Cs. Bot. Spolec. 24: 15-19.
Verloove F. & Vandenberghe C. (1995) Nieuwe en interessante voederadventieven voor de Belgische en Noordfranse flora, hoofdzakelijk in 1994. Dumortiera 61-62: 23-45.
White G.A. (1975) Distinguishing characteristics of Crambe abyssinica and C. hispanica. Crop. Sci. 15(1): 91-93.