“What are those ball things in the tree?” is a question I quite often hear asked by visitors to the palace at this time of year… “Mistletoe you say!”
As we now enter December, and the leaves on the trees have fallen, mistletoe (Viscum album) becomes clearer to see growing on the trees at Hampton Court Palace. We are lucky enough in Home Park, Bushy Park and the gardens of the palace to enjoy an abundance of the plant.
Mistletoe is unusual in that it grows from a host plant rather than in soil. In the gardens it is most commonly found on the lime trees which make up the garden avenues. It is also common to see mistletoe on apple trees, poplars, willows, hawthorn and robinia within the grounds.
The parasitic nature of mistletoe allows it to draw water and nutrients from the host tree through its ‘roots’ which are called haustoria. The plants are hemi-parasitic as their evergreen leaves photosynthesise, thus enabling the plant to produce its own sugars from sunlight.
Mistletoe is dioecious, which means that separate male and female plants occur. The male plants host yellow flowers, but it’s the female plants that are festooned with white berries which ripen in late autumn and early winter. These berries are an important food source for a number of bird species. In fact, birds are the vector for spreading mistletoe. It is common to see mistle thrushes picking at mistletoe berries in the garden; they spread mistletoe when cleaning their beaks of the sticky flesh onto branches and whilst doing so deposit seeds. Black caps, which are winter visitors to the gardens, are, I am told, by far the best at spreading mistletoe to new hosts. If you are lucky, you may see a flock of waxwings appear whilst on your winter visit to the palace gardens. Waxwings sometimes settle in one of the garden lime trees, as they did when I viewed them a couple of years ago – their chattering and flash of waxy colour is a welcome site.
For over 20 years a study of mistletoe was undertaken by volunteers within the East Front Gardens. These surveys, led by the late Tyrell Marris, recorded the progressive spread of the plant through the avenue of lime trees. It was intriguing that a number of trees became abundant in mistletoe while others remained free of the plant. I can only assume that the birds spreading the seeds liked sitting in certain trees – the ones that faced towards the palace. If trees become overburdened with mistletoe we then thin it out with hand saws.
For a number of years at Hampton Court Palace we have hosted regular ‘mistletoe walks’ with the Friends of Bushy and Home Parks. It’s traditional that they are held on the Saturday nearest to St Valentine’s Day. Although I can’t guarantee it, we are usually lucky to see a mistle thrush or two.
Nicholas Mallory Garbutt
Tree & Wildlife Conservation Manager