Last day (hooray!) of the mistletoe despatches for the English Mistletoe Shop today. Five weeks of being covered, on harvesting days, with algae from the mistletoe stems and, on despatch days, with slime from squashed berries – and all so that people can enjoy a few kisses. Is it worth it? In financial terms maybe not (don’t encourage your children to aspire to be mistletoe traders if you want them to be wealthy). Though in satisfaction terms it’s well worth it – helping keep ancient traditions alive, keeping Britain kissing and helping conserve old orchards through a mix of mistletoe management and sales.
All season I’ve been pointing out that it’s been another good berry year – with loads of berries on the female (obviously) plants reflecting a good pollination season back in February and March. But the crop hasn’t been perfect – as berries aren’t everything.
The most obvious problem this year was ripening. Mistletoe berries usually swell to full spherical shape (from oval) in late October, and ripen to a white colour (from green) in November (developing to their full translucent pearly white in December). But this season many of the berries seem to have been a month behind, with some still slightly ovoid and a little too green even now, 19th December. A few media reports have suggested this is ‘because we’ve not had enough frost yet’ – which is, of course, nonsense, as usual in many media reports. The truth is much simpler, we didn’t have enough sun this growing season – a simple fact that can be easily demonstrated by comparing the mistletoe on the sunny side of the tree with the more shady side. Guess which side has the most advanced berries? The sunny side does.
And so 2012’s wet summer did affect mistletoe a little after all – though not by reducing berry numbers as some reports would have it (Telegraph and Express, I’m looking at you) but by delaying berry ripeness a little. The seeds in those berries are most ripe, and best for planting, in February or March, so there’s still plenty of time for them to catch up before germination time.
Another curiosity this season has been the amount of algal growth on the mistletoe stems (and sometimes leaves too). Some surface algal growth on mistletoe is common, but this season has seemed exceptional, with hands and clothing often caked in green algal powder after a few hours cutting whilst up a tree. Again I assume this is due to the rather wet season we had last summer, which would have been ideal for algal growth on tree and mistletoe surfaces. We’ve found ourselves having to wash some material to make it presentable for the shop outlet – not an easy task.
And, last but not least, in the orchards we’ve worked in, there have been very large numbers of new seedlings, plus evidence of this season’s seeds already being distributed widely on stems (including on the parent plant – mistletoe has no scruples regarding what host it grows on). This new spread of seedlings, and fresh seeds, may be the result of new activity by our over-wintering blackcaps – over here in much larger numbers then they used to be. And that may be bad news for those orchards – and ultimately their mistletoe.
Proving the blackcaps’ role may be virtually impossible – but something is causing the establishment of excess seedlings… See picture left for an example of seedlings on mistletoe itself – the seedlings are arrowed, but should be obvious as odd branching that doesn’t fit the normal growth patterns.
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Details of all at www.buy.mistletoe.org.uk/growkits.htm
Great blog! I’ve linked to it from mine http://argylesock.wordpress.com/2012/12/17/mistletoe/
When you say ‘blackcap’ you mean Sylvia atricapilla don’t you? I see how more overwintering S. atricapilla would affect mistletoe seed dispersal. What confused me a little bit was the fact that N American gardeners talk of Rubus occidentalis which apparently is tasty but not well known over here http://www.garden.org/subchannels/edibles/berries?q=show&id=259
Hi, thanks for the link and the comment. Yes I definitely mean the bird Blackcap Sylvia atricapilla and not a North American species of bramble! If you browse through the blog (try this search) you’ll find lots of references to the over-wintering Blackcap phenomenon in the UK, and what it might mean for mistletoe.
Hello Jonathan, very interesting post here. Is it solely blackcap which may be responsible for dispersing larger than normal amounts of mistletoe seed or would other bird species also be contributing? Currently thinking regarding blackcaps is that the overwintering individuals in the UK are not our summer ones remaining behind after the migration, but eastern European populations from Poland, Russia and the Ukraine migrating here. I haven’t heard if that’s a climate change related phenomenon.
Hi Finn,
I’ve covered the blackcap issue many times in the blog – this post just mentions it in passing as there seemed to be a lot of seedlings about, and blackcaps are the most likely source of multiple efficient sowings. Very few birds take mistletoe berries at all, and the thrushes (the traditional/usual mistletoe seed spreaders) are much less efficient, usually swallowing the berries whole and excreting them en masse – which means most seeds never hit a branch. Blackcaps always separate the seed before swallowing and wipe it off – usually on a branch. So, lots of efficiently planted seeds does suggest blackcaps.
Re their origin, yes of course they’re not our summering ones, they’re most likely to be the new winter influx from eastern Europe. That influx may or may not be a climate change issue – I don’t know and haven’t stated that it is the case. The usual explanation is that it is bird table provision that’s attracting them, though that does seem a tad simplistic. The ‘known’ climate change issue for mistletoe is that its distribution will probably change – and may already be doing so – and observed mistletoe population changes in some areas may be due to that. To add to the confusion there is a management issue for mistletoe in old orchards in its core area – there is not enough management, leading to too much mistletoe in neglected orchard trees, which may also be leading to excess seedling growth, simply through quantities of seeds available within one small tree’s canopy.
Hello Jonathan, thank you for such an interesting reply. Will excess mistletoe growing on a tree damage it or kill it if left to grow unchecked?
I wonder why the blackcaps remove the seed from the berries. Have they worked out that the seeds are toxic? I would have imagined that the seeds may be nutritious too.
Hi Finn, yes excess mistletoe will damage a tree – and can lead to an early death of tree and mistletoe if left to take over. Not usually a problem for large trees, but can be a big issue for apple trees, which are generally smallish.
Re the blackcaps and the seeds, I imagine they wipe the seeds as they’re a little large for them and there’s no point in eating them – they’ll pass through undigested anyway, as do most seeds from berries – the nutrition for the birds is from the berry pulp and seeds are usually protected from digestion by their seedcoats. That’s the case for nearly all seeds in berries I assume – the berry merely being the plant’s mechanism for seed dispersal, via birds.
Re toxicity v nutrition, mistletoe seeds aren’t particularly toxic, though mistletoe leaves, stems and berry pulp do have some toxicity (not enough to worry about usually though). The seeds are, probably, nutritious but few animals would be digesting them with the berry – for instance mistle thrushes swallow the berries whole but excrete the undamaged seed.
But after the bare seed has got stuck to a branch after removal from the berry (via a blackcap beak-wipe, or a thrush excretion) it may become food for many small birds. The bare seeds are roughly the size and texture of a sunflower seed (i.e. one removed from its outer husk) and so are probably good eating to any small herbivore that finds them. But that’s a very different scenario to eating the berry.
You’ll find more info on many mistletoe issues via http://www.mistletoe.org.uk – there’s a survey about mistletoe management and the problems with fruit trees linked from there – or go direct to http://www.british.mistletoe.org.uk