Calluna vulgaris, in Azores.
"More Letters of Charles Darwin Volume II" by Charles Darwin
A few plants of Calluna vulgaris have been found in Newfoundland and Massachusetts, but that is not a true Heath.
"The plant-lore and garden-craft of Shakespeare" by Henry Nicholson Ellacombe
Calluna vulgaris and vars.
"Trees and Shrubs for English Gardens" by Ernest Thomas Cook