Acanthus mollis is hardy and evergreen here in the UK but flops to the ground in frost or snow. When it warms up the stems and big lush leaves rise up again. That happens to the one in the garden every year with no lasting damage. 

 I'm not sure if the same can be said of this Echium wildpretii which is a triennial in its second year of growth. The blue flowered E. pininana is naturalising in warmer parts of the UK and becoming cold hardy by a process of natural selection. Both hail from the Canary Islands but the red flowered E. pininana is still a rarity over here and probably hasn't acquired the same resistance as yet to British winters.