Other pernicious weeds
WE had no creeping cinquefoil (Potentilla reptans) here until we bought in bare-rooted gooseberries 20 years ago. A dark taproot or two must have been concealed within the rootballs, and we have been plagued ever since. Couch grass rhizomes can also cause havoc, and soft-leaved, purple-flowered hedge woundwort (Stachys sylvatica) is a spreading nuisance, as well as being a late summer host for currant blister aphid.