The Conservation Foundation is asking people to look out for elm trees in the capital. The project, called Ulmus Londinium, will map London’s surviving elm population, plant new elms and promote an awareness of elms in our capital’s heritage.

Elm sightings can be recorded on an interactive map, which is part of the Natural History Museum’s tree survey. You can view the elm tree results uploaded so far within the M25 area.

The elm was once a familiar majestic presence in fields and woodland but since the 1960s more than 20 million have been killed by Dutch elm disease.

The disease is caused by a deadly fungus that grows inside the tree trunk gradually choking the channels that transport water and nutrients around the tree. Once the disease appeared in the UK it quickly spread from tree to tree as the fungus is carried by a bark beetle.

Many butterflies, moths, beetles, fungi, lichens and mosses that lived in elm trees have also suffered as a result of the disease, as their habitat has been lost. Up to 200 lichen species have been recorded growing on mature trees, some of which only grow on elms, and nearly 30 moth species live in elm trees.

Although the elm population has been decimated, a few hundred trees at a variety of locations appear to have remained resistant to the disease over at least 60 years. It is from some of these mature healthy survivors that new saplings have been propagated. It is hoped that monitoring the growth of the new trees will shed light on why some trees are able to resist the fungal infection.

The Ulmus Londinium project is being supported by the Heritage Lottery Fund and Ernest Cook Charitable Trust. Elms belong to the genus Ulmus.