Wrong weed
Your correspondent J Davidson has failed to recognise his space-invader enemy precisely, and does the tansy a great disservice (Letters, 13 September).
Ragwort (genus Senecio) is indeed as bad as he describes, but tansy (genus Tanacetum) is a pleasant, lemon-smelling plant, used in cooking and as a tonic.
Robert Russel, The Dean, East Linton