You will not be surprised to learn that the sunflower is an introduced plant. This website includes plants that appear within our natural areas, native or introduced. Of the latter, almost all these are escapees from gardens and parks. Any discussed below fall into that category, not actually naturalised as they are not established as self reproducing in any quantity, but individuals finding an occasional opportunity.
ANNUAL SUNFLOWER : Helianthus annuus
The Annual Sunflower is a non-native annual plant now found across much of the UK. It thrives on disturbed land and can reach up to 3 metres in height. The Native Flower website tells us that it was introduced as a domesticated crop into Europe and brought to the UK in the sixteenth century.
It is thought to be named after the sun-like appearance of its large golden composite flowers. They have a central area of tightly-packed disc florets, surrounded by the ruffled petals of its ray florets. the sun-seeking habit of its flowerheads. The name Sunflower may also be associated with the plant's sun-seeking habit while it is developing, moving its flowerheads daily from east to west to track the sun as it moves through the sky (although mature heads stay oriented towards the east).
It can be surprising where sunflowers can be found growing quite happily. This one was spotted in an isolated rocky area of the upper Leven that is flooded several times a year. While it has been impossible to get closer to it for verification, it appears to be an annual sunflower.
NATIVE FLOWER website : https://www.nativeflower.co.uk/details.php?plant_url=66