Did you also notice that it was GEORGE Chaucer, whoever he was....just to add to the confusion.
I agree it was not a terribly good round unless we have missed the point completely. After all one can hardly be specific to the exact year in a lot of cases as to when plants were introduced. As to Lavender, I did find some reference to the fact that the ENGLISH varieties were not developed until c1600 but, yes, the French type had been around for centuries...... so it is not clearexactly what is wanted