Mistletoe is a familiar Christmas staple, soaked in folklore and midwinter tradition. But where does it grow and how can you find it in the wild?
What is mistletoe?
Mistletoeis an evergreen plant with distinctive forked branches and pairs of symmetrical evergreen leaves. In winter it produces clusters of pearlescent white berries which are favourites with hungry birds such as thrushes.
The plant is 'hemiparasitic', which means it takes some of its food from another plant. It grows on the branches of trees, pulling water and nutrients from its host, while its green leaves also photosynthesise.
There are more than 900 species of mistletoe around the world. The only species native to the UK is European mistletoe (Viscum album) which has thewidest host range of all its relatives.
Where to find mistletoe
Mistletoe grows in the branches of trees such as hawthorn, poplar and lime, although in the UK the most common hosts are cultivated apple trees.
Despite growing on trees, mistletoe is not generally found in a woodland setting, preferring hosts in open situations with plenty of light. You’re more likely to see it in gardens, orchards, parkland and even churchyards. This means that mistletoe would have been less abundant in ancient times when woodland was more typical.
It's commonly found in Wales, the west Midlands and the south of England, with particularly large populations in Gwent, Herefordshire, Worcestershire, Gloucestershire and Somerset. It was once thought that this clustering was due to the number of apple orchards in these regions, but this has been proved to be incorrect as orchards are found in locations where mistletoe is absent. Mistletoe is widely scattered elsewhere in England and Wales, but is rarely seen in eastern and northern England and Scotland.
How does mistletoe spread?
In recent years, mistletoe's range in the UK has begun to expand, particularly into eastern areas of England. This may be due in part to an influx of continental blackcaps from Germany that have started overwintering in Britain, with many thousands now spending their winters here.
Blackcaps are migratory warblers that are becoming regular winter visitors to our bird tables. Berries, including those of mistletoe, are an essential part of their diet. On eating the white flesh of the mistletoe berry, the birds wipe their bills on twigs and branches, leaving behind the seed. If the seed is deposited on a host tree and manages to take hold, a mistletoe plant might germinate on the branch. It seems that blackcaps are more efficient at spreading mistletoe seeds than other birds that feed on the berries.
Is mistletoe important for wildlife?
You should always obtain the landowner's permission before gathering mistletoe from the wild. It is also important not to take too much.
The mistletoe marble moth (Celypha woodiana) needs this unusual plant to complete its life cycle. Its larvae overwinter in small mines chewed into the leaves of the plant, which become inflated by late spring when the larvae are fully grown. The larvae then emerge from the mines and pupate in a cocoon under bark or among lichens on the host tree.
The mistletoe marble moth is a priority species for conservation in the UK. It is only found in six English counties, and populations are declining. It is thought that the amount of mistletoe harvested in these counties poses a threat to the future of this already rare species.