Features
This evergreen plant flowers in February and March with small, green flowers. It is dioecious (meaning that there are separate male and female plants, of which only females have berries) and pollinated by insects. It takes a year for the berries to fully ripen, hence they are available through the winter and fully ripe by February/March.
Viscum album grows on deciduous woody plants. Some species of mistletoe are very picky about the plants they’ll grow on, but Viscum album is happy to grow on a wide range of hosts, particularly apples, limes and poplars.
What to use it for
Mistletoe is very useful for wildlife gardening as a many birds, particularly European blackcaps and mistle thrushes (who are so named because of their taste for mistletoe berries), consume the berries. Beyond the UK mistletoes can also provide excellent nesting habitats for birds. But the main reason people grow mistletoe is to use it as a traditional Christmas, mid-winter or new year decoration.
How to look after it
Mistletoe is a partially parasitic plant. It can photosynthesize to produce energy, however it relies on its host for water and minerals.
It spreads to new hosts by the seeds sticking to tree branches (the flesh of the berries is very sticky). Upon germination the seed sends out more or more hypocotyl which penetrate the bark to the cambium layer. The seed and hypocotyl both photosynthesize and rely heavily on light in their early months of development, so if you’re trying to grow mistletoe don’t put the seeds under the bark or in a dark crevice.
The mistletoe’s plumbing (the ‘xylem‘ vessels) combine with that of the host, and the mistletoe uses this to draw on the host’s supply of water and dissolved minerals. As the xylem vessels grow together this causes a small area of swelling called the ‘haustorium’. The mistletoe continues to grow along the branch dropping new shoots into the bark. Often the branch will die back to the point of infection as the mistletoe monopolises the water and mineral supply, this doesn’t tend to pose a problem for mature trees, but can kill young ones.
How to prune it
Once your mistletoe has established, prune it back each year, removing about a quarter of growth each time, cutting each stem back to the host’s bark. This will ensure that the mistletoe doesn’t become too large and threaten the health of the host tree. Removing entire stems, rather than just cutting back the tips of all the stems, will ensure that you still get berries that winter (the berries grow from the stem tips). Always cut back male mistletoe plants as well as female ones, even when you’re harvesting for Christmas decorations.
You can renovate mistletoe by cutting it right down to the bark, it will re-sprout.
How to propagate it
Sow seeds in early spring, fresh berries are best but you can store them from Christmas if they are kept in cold and light conditions (eg in your shed). If you have stored your berries, rehydrate them in a little water for a few hours before planting.
Choose a young 2-6cm diameter outer branch and squeeze seed from the berry, remove most of the sticky jelly-like substance as possible, and press it onto the side or underneath of the branch – so it will have light but won’t get dried out. Stick many seeds on each branch and use a few different branches to maximise chances of the seeds taking and of getting both a male and female plant. Keep in mind that branch may die back beyond the point where you’ve planted the seeds and that the mistletoe will reduce fruit yield on apples.
You’ll see no real change for about 18 months, at which point you should see a slight swelling and the first leaves growing. It will be at least 4 years before you get any berries.
Common problems
Mistletoe itself can be considered a problem, particularly if found on a very young plant or a branch which you want to save. If caught at an early stage, the mistletoe can be cut out of the branch, removing the wood of the swollen area (haustorium) as well as the external growth. Once you think you have removed the mistletoe keep an eye on the tree for a few years as it can re-grow from the haustorium if you left any of it inside the branch.
There are a few pests which affect mistletoe, including a weevil whose larvae develop in growing the tips, killing terminal buds and reducing next season’s fruit crop.
Other useful information
All parts of mistletoe are toxic, so be careful that bunches hung around the house remain out of reach of children and pets. Mistletoe is used in herbal medicine, but should only be taken if prepared by an experienced practitioner.
There are as many as 1,500 species of mistletoe around the world, including Viscum cruciatum which grows on olives, Arceuthobium oxycedri which is a dwarf mistletoe found on junipers and Loranthus europeaus which is a deciduous, yellow-berried mistletoe growing mainly on oaks.
The botanical name Viscum album derives from the sticky (ie ‘viscous’) juice from the white (album) berries. The common name ‘mistletoe’ is thought to have originated from the Saxon ‘mistl’ meaning ‘different’ and ‘tan’ meaning ‘twig’, presumably referring to the doubling of the stems with each season’s growth. Another theory is that it derives from ‘mist’ meaning ‘dung’ and relates to the way the plant is spread through bird excrement.
There are many myths and traditions surrounding mistletoe. Pliny the Elder (23-79AD) mentioned its use by Druids and mistletoe features in myths from Greek, Roman and Norse traditions. Today mistletoe is seen as a symbol of peace and luck. The tradition of kissing under the mistletoe at Christmas probably derives from its use in fertility rituals.
