(Photo above: Mistletoe in Central Milton Keynes © Mary Sarre)

My interest in this curious plant has been stimulated in the last couple of years, by coming across several occurrences locally, in Milton Keynes. This seemed to me quite odd, as I associate mistletoe with the apple orchards of the south-west, the orchards of Normandy, and poplar trees festooned with it in France (seen from the Autoroute).

So here is a little contribution to the botany of mistletoe, its distribution and association with certain birds, traditional beliefs and folklore, and some sightings here in MK.

Viscum album, to give it its Latin name, is a good indicator of its characteristics – it has the well-known white berries, which are viscous (sticky), in winter, giving rise to its traditional association with mid-winter festivities.  White-berried plants are unusual except in MK where the ‘snowberry’ (symphoricarpus) is used massively in grid-road plantings. Whether the snowberries are consumed by birds I don’t know, but the flowers do attract pollinating insects. Mistletoe is dioecious, i.e. having male and female parts on different plants. The leaves and stems are light green, typically branched at each node, producing a new ‘fork’ each year.

Viscum album by Stella Ross-Craig, 1969 (see references below)

Mistletoe is semi-parasitic on a range of trees, but the main ones are Apple (Malus), Lime (Tilia), Pear (Pyrus), Hawthorn (Crataegus) and Poplar (Populus), occurring in orchards, hedgerows, parks and gardens. It is not generally found in dense woodland (Simon Harrap, 2013).

Mistletoe occurs chiefly in the south of England and Wales, in lowland areas. It is spreading from the old orchards of its Herefordshire heartland to different species of trees in parks and gardens in Hereford, Ledbury, Bridgnorth and Westbury-on-Trym (Mabey, Flora Britannica). South Bucks and Hampshire are also ‘hot spots’.

Dispersal

In medieval times mistletoe seemed ‘magical’ in its appearance high in the host trees, evergreen and of a curious growth habit, appearing to spontaneously sprout from the tree. For centuries, mistletoe retained its magical, folkloric associations (see Richard Mabey for a wide-ranging account), and today its medicinal properties are still under investigation.

It was Philip Miller, curator of the Chelsea Physic Garden, who discovered that mistletoe could be established by smearing the sticky seed onto a suitable branch.

However, it is famously resistant to propagation by human hands (“none of the seeds placed on 14 different apple species in Kew Gardens in 1996 ‘took’ but one grew on an adjacent Hawthorn”. (Dr Ken Thompson, Gardening Which?, December 2020).

For long it has been assumed that the Mistle Thrush (Turdus viscivorus) was the primary disperser of the berries, as it attempts to remove the mucilaginous outer coat of the berry, raking its beak along a branch of the tree, and leaving its droppings in the tree.

Mistle Thrush ‘guarding’ his patch (Photo courtesy of The Woodland Trust)

To quote Dr Ken Thompson again, it appears that the Blackcap may now be a more effective distributor of mistletoe. He notes that the mistle thrush swallows the berries whole, and ejects the seeds randomly in its droppings. The Blackcap however eats only the skin and pulp of the seeds, wiping the sticky seeds off their beaks onto a branch. Once the seed is attached to a suitable branch, it sends out a ‘root’, a ’haustorium’ which penetrates the xylem of its host. The seeds are photosynthetic, so they need to be in the light.

Blackcaps, formerly mostly a summer visitor, are now frequently spotted in UK in winter (MKNHS sightings, November 2020). According to an article by Helen MacDonald, in Vesper Flights, German Blackcaps that have started spending winters here rather than in Africa may be directly responsible for spreading mistletoe to new areas of the British Isles. Which brings us back to our local area.

Local distribution

My notes cannot claim to be exclusive, and I would welcome any sightings from members. The first time I saw any mistletoe was in Great Linford Manor Park, a couple of years ago, in the venerable old lime tree near the canal. There are two balls/orbs high in the tree, obviously more visible in winter time (the park is open all year round). Julian Lambley drew my attention to another occurrence – in Simpson village – several orbs in two old Lime trees.  This made me wonder if the canal and the Ouzel valley could be the ‘corridor’ for extending the range of the Blackcap or Mistle Thrush.

A last sighting, in Central Milton Keynes, possibly on a young lime tree gave me pause – perhaps the mistletoe was ‘injected’ on a limb before planting, or a human hand was involved?

Mary Sarre
January 2021

Sources
Dr Ken Thompson, Plant ecologist, (Gardening Which?, Dec 2020 / Jan 2021)
Richard Mabey, Flora Britannica (Sinclair-Stevenson, 1996)
Stella Ross-Craig, Drawings of British Plants, Vol XXVI (Royal Botanic Gardens, Kew, 1969)
Helen Macdonald, Vesper Flights  (Jonathan Cape, 2020)
Simon Harrap, Harrap’s Wild Flowers (Bloomsbury, 2013)