The wall was part of the original boundary of the Roman city
Officials in St Albans are concerned that sycamore trees could damage the city's remaining historic Roman walls.
The wall in Verulamium Park was built between 265 and 270 AD and was part of the original boundary of the Roman city.
An important example of Roman building work, the wall would originally have stood five metres high and three metres wide with a walkway on top.
It would have extended for some two miles around the city.
After fears that the sycamore trees could ruin the brickwork, St Albans District Council decided to address the problem by removing any seedlings as they appear.
The sycamore seedlings are being removed
Chris Green, the Museums and Heritage Officer at St Albans District Council told the BBC that the trees are an important part of the park:
"The trees make a vast contribution to the park. If you were to imagine the view without trees, I think you would find it a much poorer one.
"The Roman wall has had trees growing over it since late Roman times, and has in fact been a wooded area for some 1600 years," explained the council officer.
"The wall is carefully maintained, extremely robust and not in great imminent danger.
"However we do want to stop any damage occurring by small rootlets."