Thankyou for the further information ontarioice.
Yes, bitter vetch was first named as Ervum ervilia by Gerard, who was a botanist in the 16th Century, and the name is now noted as a synonym, but since then the Latin name has changed and is now placed in the genus Vicia, as Vicia ervilia (L). Willd.. Linnaeus and the German botanist Willdenow came afterwards in the 18th Century who came up with the new nomenclature.
Thank you very much for your comments and explanation.
It truly has been an expanded education joining the Aber site. I mean that lest you think I am trying sarcasm.
I wish I had a great big file folder in which to store the new things I learn daily - and I thought I was educated.
However, re the original question do we agree that "ers" refers to Ervum ervilia? It's only a crossword puzzle, but I don't want anyone to think I was trying to mislead.