Viscum album, the scientific name for European mistletoe, tells us two things about the plant – it is viscous and white. Both attributes apply to the berries – which are pearly, translucent white when ripe, and, if you squeeze one, full of a very very sticky white liquid.
And they’re just turning white now, the end of October/ beginning of November, having been green since the early spring. But only on the sunny side of the tree… berries in the shade still seem to be rather white, even now. Looking around the mistletoe on apple trees in Painswick today I found every colour from green, white with green hints, through to full pearly white.
Now berry colour is a big issue with our mistletoe – it is very variable even within Viscum album and its many subspecies. Some, in central Europe, are almost yellow when ripe (the variations have been studies by Dr Grazi in Switzerland) and there are many creamy variants too. Down in Spain and Portugal there is a red-berried variety – though this is, properly speaking a different species Viscum cruciatum – but I have seen papers suggesting even this is merely another colour-variant of V album.
Another issue here is recognition by birds. Studies have shown that many birds simply don’t recognise white mistletoe berries as food – they are tuned in to the usual red, blue, black and orange jobs, but not the more unusual white ones. This isn’t really surprising as mistletoe is the only native white-berried species in northern Europe. It has specialist feeders of course – notably the Mistle Thrush, whose latin name, Turdus viscivorous, translates as the ‘mistletoe-eating thrush’. Which seems logical, until you realise it was named (by Linnaeus himself) after its predilection for the berries of V cruciatum in Spain – which being red, doesn’t fully explain why it’s so fond of the white V album.
Maybe it just likes sticky berries. Contrary to popular legend, the mistle thrush doesn’t wipe the seed from its beak and swallow just the berry pulp, it swallows the whole lot, and craps out the seeds en masse, in a partially-digested sticky residue left over from the seeds.
And guess what, the seeds are green – already photosynthetic, the embryonic mistletoe plant already producing its own sugars by photosynthesis. This pic, taken this week, shows a string of the seeds, recently deposited by a Mistle Thrush. It’s a little early in the season for successful germination (that’s best in February) but it looks as if the top seed in the line is already germinating. Good luck to it – the bark looks a bit thick here!
It’s not just Mistle Thrushes that recognise and eat mistletoe berries – other Thrush family members join in – inc Blackbirds, Fieldfares etc. And Blackcaps, from another bird family, play abig part too – and they are rather more fastidious, wiping each seed from their beak before swallowing the pulp. Much better manners than Mistle Thrushes.