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Thanks to its association with Christmas, and its appearance on cards and decorations, Mistletoe is probably one of our most recognised native species. This association also means that the ‘kissing plant’ is also harvested in huge volumes each year for seasonal decorations. That tradition probably derives from a long history of use in ritual, which may have started with Celtic druids.

It’s seen variously as a symbol of fertility, love, and peace across European cultures. However, the kissing tradition itself appears to have developed more recently, perhaps in the 18th century.

More about Mistletoe

But what of the plant in the wild? Although it has a widespread distribution in the UK, it is quite rare in many areas. Its greatest abundance is strongly clustered around the Welsh-English border areas.

In fact, it’s also the county flower of Herefordshire, where you can find our Joan’s Hill Farm Nature Reserve. Here, it is strongly associated with the area’s fruit orchards, although it grows on a wide range of deciduous trees such as poplars and limes as well as orchard species.

The life of a parasitic plant

Mistletoe is an ‘obligate hemi-parasite’ of the trees on which it grows: that is, it doesn’t just grow on trees as a physical host. It actually can’t survive without the biological symbiosis it has with the host tree, although it does also photosynthesise. So how does that relationship work?

Mistletoe produces seeds in white berries – itself unusual, being our only native plant with truly white berries. The seeds are spread through the landscape by birds, such as thrushes (via their droppings) and Blackcaps (which move seeds mechanically on their bodies).

Both routes allow seeds to stick to new tree hosts, where if the location is suitable, they germinate. The young emerging seedlings are photosynthetic, and so at this early stage they are not dependent on the tree.

As the seedlings grow, some shoots penetrate the bark of the tree and connect with the tissue beneath- the beginnings of the parasitic relationship. In the plant’s first year, its connections with the tree’s tissues already provide it with water and crucial mineral nutrients.

It’s only then, over the following few years, that the plant very slowly begins to grow. Mistletoe is a long-lived perennial.

How does parasitism work?

Parasitism is a form of symbiosis where one partner benefits at the expense of the other. Mistletoe thrives on account of the tree, but the reverse is not true. If a tree has a lot of Mistletoe, it can eventually affect the tree quite severely, impeding growth, and for example, making it more susceptible to drought as a result of water loss.

Parasitism has evolved multiple different times across the plant world. The largest flower in the world, Rafflesia arnoldii, is the flower of a parasite. There is a parasitic conifer, Parasitaxus usta, that grows in New Caledonia, and Hydnora africana looks like it comes from a scifi movie.

Discover more parasitic plants in the UK

In the UK we have a wealth of parasitic and hemi parasitic plants that gain nutrients directly from other plants as well as a whole bunch of plant species that rob their nutrients either fully or partially from fungi.

  • We have 21 different species of eyebright, Euprasia, in the UK. Some, like Euphrasia cambrica, (pictured) are found here and nowhere else in the world. The beauty of eyebright flowers is best viewed with a hand lens. Some eyebright species can be seen in abundance during the summer at nature reserves such as Caeau Tan y Bwlch in North Wales. Here you can find rare Euphrasia monticola alongside thousands of Greater Butterfly Orchids.
  • If you happen to be in your local supermarket carpark it is worth looking out for the newly described variety of broomrape, Orobanche minor heliophila. This variety of Orobanche minor was only recognised in the UK in 2020. This plant is only found growing with a shrub from New Zealand that is often planted in carparks called Brachyglottis × jubar ‘Sunshine’.
  • We have two species of toothwort here too – one, Lathraea squamaria, is native and associates with Hazel trees; the other, Lathraea clandestine, was introduced as a garden plant and will happily parasitise several different trees and shrubs without doing them any serious harm.
  • Yellow Rattle, Rhinanthus minor (the meadow maker) is a hemi parasite and we use this feature in wildflower meadows to reduce the vigour of grasses and benefit the other plants. Its relative is Rhinanthus angustifolius is now very rare in the UK. Eyebrights, cow wheats, louseworts and bartsias also serve the same role as yellow rattles in meadows and woodlands.
  • We have 14 different species of broomrape many of which only associate with a single, or a very small number of, host species. Broomrapes are spectacular plants and rival many of our terrestrial orchids for beauty – it’s worth going out and trying to see some of them. The easiest ones to find are probably Ivy Broomrape or Common Broomrape
  • Possibly the most vampire-like parasitic plants we have in the UK are the dodders, Cuscuta. Three species of dodder are found here, two are native and one is introduced. When they germinate, they can ‘sniff out’ their host plant species which they then twine around before the penetrate the hosts stems to extract nutrients with haustorium – rootlike structures that absorb water or nutrients from the host.
  • Many orchids like Neottia nidus-avis, the Bird’s-nest Orchid, and heather relatives such as Monotropa hypopitys, the Dutchmans Pipe (pictured), extract all their nutrients from fungi without providing anything back to their host. This is a type of parasitism called myco-heterotrophy.

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