There are about 1500 species of mistletoe around the world, and all of them are shrubby plants that grow parasitically on trees. Most grow in the tropics and subtropics, with relatively few species in northern temperate areas.
Exact numbers, and their botanical classification system, are both variable, depending on current fashions in botanical naming. There are, traditionally, two main mistletoe families, the Viscaceae (which includes our Viscum album) and the Loranthaceae, which includes many of the more colourful tropical species.
The Viscaceae is currently considered (under the current APG system) to be a subgroup of the much larger Santalaceae, or Sandalwood family. That family includes many other parasitic species as well as the former Viscaeae species.
Other European mistletoes
There are a handful of other mistletoe species within Europe. The most striking is the red-berried Viscum cruciatum, mostly found in Spain. It is very similar to V.album, differing largely in berry colour.
We also have one species of Dwarf Mistletoe, the mistletoe group that causes so much damage to forestry in North America (see notes on American mistletoes below).
Ours is Arceuthobium oxycedri, a tiny mistletoe found on Juniper bushes and trees in Spain and around the Adriatic coast and Greece. You have to look hard to find this one.
We also have one member of the Loranthaceae mistletoes, which are more at home in the tropics.
This is Loranthus europeaus, a yellow-berried species that grows mainly on oak trees in central southern Europe.
A mistletoe that likes oaks may sound exciting, especially to those inclined to Druidism, but sadly this species is deciduous, so it doesn’t have the cachet of our evergreen Viscum album in winter.
North American Christmas Mistletoes
There are many mistletoe species across North America, but the best-known are the Phoradendron species, a group used at Christmas instead of the original Viscum album of Europe.
Though allied to Viscum, the Phoradendron species look very different, lacking the symmetrical branching patterns and leaves of Viscum and looking, to be frank, fairly ordinary. But they do have evergreen leaves and white berries in common, so can be considered a rough match.
Their ordinary appearance does cause a little confusion though, and there is some evidence that some Americans now use Holly, a much more distinctive plant but certainly not a mistletoe, for the kissing custom!
The American Phoradendrons, often simply known as leafy mistletoes, are southern species, with most of the Christmas supply coming from southern states, notably Texas.
Europe’s Viscum album has colonised a few areas, notably in Sonoma County, California, but it is considered a potential forest pest and growing it in the USA is now prohibited
North American Dwarf Mistletoes
Other mistletoes in North America include the Arceuthobium species, or Dwarf Mistletoes. These tiny plants have small scale-like leaves, are almost holo-parasitic (most mistletoes are only hemi-parasitic).and can cause significant damage to forest trees.
These mistletoes are so damaging that there are many publications and guides to their control.
One of the most comprehensive publications is US Agricultural Handbook 709: “Dwarf Mistletoes: Biology, Pathology, and Systematics”. If you’re interested it can be downloaded here.
Africa has hundreds of mistletoe species, with most from the showy Loranthaceae, whose long colourful flowers are a complete contrast to our European Viscum.
But Viscum species occur there too – indeed over 40 species of Viscum can be found in mainland Africa and over 30 more in Madagascar.
Two contrasting species are pictured here, the tiny Viscum minimum and the more conventional V. triflorum..
The Loranthaceous mistletoes are Africa’s most obvious and characteristic species.
There are far too many types to discuss in detail here so, if you’re interested why not buy Roger Polhill and Delbert Wiens’ book Mistletoes of Africa. Published by Kew Gardens in 1998, the book covers the biology and phytogeography of all the African species and describes several hundred species, in both the Viscaceae and Loranthaceae.
The cover picture of the book shows the flowers of the loranthaceous mistletoe Spragueanella rhamnifolia.