10. Rumex rugosus Campd. (syn.: R. ambiguus Gren., R. acetosa subsp. ambiguus (Gren.) Á. Löve) (origin obscure) – A rare but probably overlooked, ephemeral garden escape. Formerly frequently cultivated as a vegetable (sorrel) but much decreasing nowadays. Seen in 1954 on a dump in Namur and in 2007 on a dump in the port of Gent. In the past years increasingly seen in wild flower seed mixtures and sometimes temporarily persisting.
Rather poorly distinguished from native Rumex acetosa and possibly merely a robust variant of the latter. Also rather reminiscent of Rumex thyrsiflorus.