The magicof mistletoe

Thanks to our wetter climate – and its own survival instinct – this romantic symbol of Christmas is more abundant than ever, says

Much of the mistletoe that will be bought this Christmas comes from abroad, as you often have to wait until as late as February for our native mistletoe to reach that ideal Christmas card state of sticky, milky berries. Not this year. The mistletoe was in full berry as early as September and I thought it might all be over by now. I’ve never known it be ready so early. It’s always variable but this does seem extraordinary and almost certainly another of those tangible examples of climate change that every gardener cannot help but notice.

I suspect that outside the few weeks astride of 25 December few people give mistletoe any thought at all. In my own garden, however, I see it in quantity every day because it happens that we’re right in the epicentre of the British mistletoe population. It first appeared in my orchard about 25 years ago as a single bunch on an old hawthorn tree in the hedge but has now progressed from the occasional tiny sprig to dozens of sprouting globes growing on almost every one of my apple trees.

Climate change is probably one reason for this proliferation but the relationship between mistletoe and its choice of host and the way it is spread are others. Mistletoe seems to be very picky about the trees it likes to grow on. The image of druids and mistletoe growing on oak is misleading because to see mistletoe on an oak tree is vanishingly rare. Its preferred hosts are, in descending order, apple, lime (tilia), hawthorn, poplar, field maple and willow. Although it is a plant of trees it likes plenty of light and air around it so is not often found in dense woodland, much preferring gardens, parks and orchards. It favours lowland in the wetter west of the country and it does seem that our milder, wetter winters and summers are very much to its liking.

It is also suspected that climate change has meant that continental blackcaps, a winter visi- tor to our bird tables, are overwintering much more in the British Isles and they are one of the most efficient and effective distributors of mistletoe seeds. These are spread by birds eating the berries and then wiping the sticky seeds off their beaks on a branch, or by the seeds passing undigested through the bird’s body and being deposited later. The seeds are naturally sticky so do not need to land on rough bark, let alone be put under a lifted flap of bark. Once they have germinated the new growth will quickly sucker itself to the host and the roots will take nourishment from the branch and eventually strangle it, killing the mistletoe in the process.

The seedlings grow very slowly at first and are barely noticeable for a year or two, but by year four a young plant is clearly visible with its characteristic bifurcation – that is, when the stem divides in two – and each branch on each sprig will bifurcate every year, so by a process of compound interest mistletoe goes from a small outgrowth to a large round ball pretty quickly.

If you have mistletoe growing on your apple tree you can combine harvesting some every year for Christmas decoration with helping the tree to cope with this (semi) parasite. Remove a third of the bunch each year and both parties will continue for a long time. It is not a true parasite insomuch that the evergreen foliage does photosynthesise and provide nourishment for the mistletoe, but not enough to keep it alive independent of its host. If the tree dies the mistletoe will die with it.

I am now off to preserve my apple trees by gathering some bunches of mistletoe for my own Christmas decorations.

Monty with his mistletoe