Studies of European mistletoe’s host preferences often show distinct preferences for particular varieties, or cultivars, within a tree species – so that some varieties of Apple tree are more susceptible than others, as are some varieties of Lime tree, Poplar tree etc.
Demonstrating this convincingly on the ground is difficult – as you generally need a lot of data for lots of trees.
But on Christmas Day this year I suddenly found the perfect demo virtually on our doorstep! And wondered why I’d never noticed it before…
Some background: We live on the edge of Stonehouse, not far from the old Standish Hospital, a rural former NHS hospital now standing empty and decaying in its own grounds – which are a mini-arboretum, with many splendid exotic mature trees. The driveway up to the site has an avenue of relatively young (maybe 30-40 years old) ornamental maples.
Now, we’ve been here over 14 years now, and have walked that drive regularly, as there’s a bridleway route though the site. And over those years we’ve watched as mistletoe has established in those maples, colonising from existing mistletoe colonies in the remnant apple orchards nearby (there’s an old orchard at both ends of the drive) and from mistletoe in nearby poplars.
The revelation: The mistletoe in the maples is now fairly well established – and on Christmas Day afternoon, as we wandered up the hospital drive and back in an effort to walk off some lunch, I was idly assessing the mistletoe in each tree (as one does) – and suddenly realised that… every other tree in each side of the avenue was mistletoe-free. And the mistletoe-free trees were never opposite across the avenue either. So, if plotted on a map the mistletoe trees would be a zig zag pattern along the drive.
And why would that be? Well, these maple trees are two varieties – one a red-leaved one and one a green-leaved one – and they are planted in an alternating pattern. So… the mistletoe, which we’ve witnessed developing over the last 14 years, is only colonising one of the maple varieties – not the other. Which one? Well I think it is the red-leaved one – but will have to wait until spring for confirmation. The aerial photo on the right, when compared to the mistletoe pattern we’ve seen (we checked it again today), seems to confirm red though.
So, there you have it – mistletoe colonising one variety of a tree but not another closely related one – despite having decades to do it in and the trees being right next to each other. I’m just slightly embarrassed that I’ve only just noticed!
Monty’s at it again! His annual mistletoe misinformation project is reduced to one small paragraph this year, published as usual in that bastion of misinformation, the Daily Mail. For comment on one of his longer previous efforts have a look at the the Mistletoe Diary for Dec 15th last winter.
Here’s the new article line by line – with my comments
MONTY’S PLANT OF THE WEEK (Daily Mail 28th Dec)
Mistletoe (Viscum album) “Mistletoe is a parasite.” Almost correct – mistletoe is a hemi-parasite, as it produces its own metabolites through photosynthesis, just like non-parasites.
“The seed is deposited on the bark of a host tree and puts its root into the branch, tapping into its nutrients.” Yes the seed is deposited on the tree’s bark but it doesn’t have ‘roots’ and doesn’t grow ‘into’ the branch – it just penetrates the bark and make the tree’s growth cells grow around it. The only nutrients it takes are from the tree’s xylem system, which is just water and minerals from the soil, not the tree’s own metabolites.
“As the mistletoe grows outwards its roots are growing inwards.” See comments above – mistletoe does not have roots – and does NOT grow inwards – it makes the host grow outwards around it… (and so creates an illusion that it grows inwards – which is a remarkable phenomenon and surely worth mentioning Monty? ).
“Eventually these block the tree’s nutrient supply and the branch dies, killing its parasite with it.” No (see comments above) – though the branch and tree will be much stressed by the mistletoe and too many mistletoes will hasten tree death. For more on the actual mechanisms Monty might try actually reading it up – he could start with some of the info I reviewed here recently on mistletoe and tree mortality – it’s absolutely fascinating stuff and, again, surely worth covering truthfully Monty??
“Mistletoe loves apples, hawthorn and poplar, but no one knows why it grows in some places and not others, although air quality and humidity seem to be important, as does the migration pattern of birds such as blackcaps that excrete the seed onto suitable branches.” Where to start with this one?? Yes the tree list is accurate, but reasons why it grows where it grows are fairly well understood (though obviously not by Monty) and have nothing to do with air quality (is he getting it confused with lichens???) and whilst blackcaps have a role, their winter role in Britain is only recent, in the last few decades, so is most definitely NOT the reason for mistletoe’s established distribution.
And blackcaps wipe the berry – they don’t excrete it. That might seem a minor point but it’s not – it is fundamentally important to how new winter populations of blackcaps might be gradually changing mistletoe distribution – perhaps the most fascinating mistletoe fact of the moment – which is extremely newsworthy and gardening-relevant – though, sadly, it seems to have passed by Monty entirely.
As I said last year, though not in these words, how does he gets paid for this tripe?
If it was written by a non-specialist it would be forgivable – but such inaccurate info from a ‘gardening expert’ is not, in my view, acceptable. .
Commercial break – if you want some accurate information on mistletoe…
Mistletoe and candles – I’ve discussed this before, and as my regular reader knows, have no truck with any of those ‘mistletoe-scented’ affairs – which are all fakes, as mistletoe doesn’t have a scent. For previous diatribes see relevant blog entries from 2011 here and 2010 here.
But earlier this year the Mistletoe Shop was approached by Lesley Sparks, of The Hedgewitches Garden, who wanted to produce mistletoe candles and melts, and needed to obtain some mistletoe out of season for their manufacture.
Did she know it was scentless? Yes she did, and was more interested in incorporating mistletoe into the product, rather than any supposed scent. Her aim was to ‘celebrate the magic & mystical influence of Mistletoe’ by incorporating leaf fragements in the wax – the scent was to come from other ingredients.
Lesley recently sent me some of the mistletoe melts to try (thanks Lesley). And we have tried them and can confirm that they are beautifully-scented – with a mixture of Sandalwood, Cedarwood, Oakmoss, Lemon & Bergamot. The mistletoe is visible as leaf fragments.
So, at last, an honest mistletoe candle/melt – mistletoe-branded but not pretending to be mistletoe-scented!
The Sandalwood scent is a particularly nice touch, though I’m not sure whether it is deliberate. Why? Because sandalwood and mistletoe are quite closely related. Our mistletoe Viscum album is in the botanical family Viscaceae, which is part of the wider botanical order Santalales. And that includes the Santalaceae or Sandalwood family. Indeed recent taxonomic opinions have lumped the Viscaceae within the Santalaceae family – meaning the two plants are now considered to be more closely related than previously believed. So a Sandalwood-scented candle is particularly appropriate for a mistletoe-theme.
Plenty of stuff yet to come for the Mistletoe Diary this year – though I’m a bit behind schedule.
Time for some light relief from San Francisco, where “interactive artists” (what does that actually mean?) George Zisiadis and Mustafa Khan have made a Mistletoe Drone out of a Parrot AR.Drone (pictured in unaltered form on the right).
They wrapped their drone in tinsel and mistletoe and have taken it to Union Square in San Francisco to buzz unsuspecting couples.
Zisiadis is quoted as saying
“All my work is about playfully re-imagining the world around us. Drones have been causing all sorts of paranoia lately and I wanted to reframe them from being something scary and ominous to being fun and human. It’s not about the technology, its about how we use it.”
“Buy British!” That slogan doesn’t have the same ring about it these days, when so many products are imported, but surely mistletoe is one of those few that we could, in theory, realistically aspire to buy locally. There are regular calls each year to make sure your mistletoe is British, backed up with the idea that this will sustain our native mistletoe industry. But is this at all realistic?
There is no labelling scheme – so, frankly, most florists/greengrocers won’t have a clue where their mistletoe came from. The only significant home-grown supply is from mistletoe-filled orchards in the SW midlands of England – and those orchards are on the decline. And, despite media-hype, we have relied on mistletoe imports from mainland Europe since at least the late 19th century.
Are those imports a problem? Not as far as I can tell. Up until the 1960s or so, when imports still came via traditional means, it was normal for the British media to report on the import figures – with tonnages of mistletoe imports reported as a ‘good thing’ and part of the Christmas seasonal events. Since the 1990s, when worries about home-grown mistletoe supplies began, the opposite line has been taken – with the media implying that imports are somehow bad, and a ‘new’ phenomenon.
Reports from the late 19th century describe ships with deckfuls of mistletoe coming over from France – there’s a Worcestershire example on the left. And when the French government passed a law obliging their orchard owners to control mistletoe there was understandable angst here in Britain (see the 1895 story on the right)
Press photos from the 1920s, 30s and 50s feature Normandy farmers cutting mistletoe for export to Britain. It was an accepted, and expected, part of the seasonal news.
The import trade continues, though it’s not so well reported these days, perhaps because there is so little regulation on cross-border trade now, particularly within the EU. This makes it much less obvious.
But should we be worried by it – do mistletoe imports threaten our home-grown mistletoe trade and harvest? I suspect there is no problem – indeed the recent trend to publicly despair of imports is probably ensuring the home-grown trade is doing better than ever, especially with the new UK-branded mail-order retailers set up on the internet (which are the only effort at a ‘Terroir‘ system we have for mistletoe).
The real problem is sustainability – and that applies to both the home-grown and imported mistletoe. Most mistletoe, wherever it is harvested, comes from old-style traditional apple orchards and those are just as threatened in mainland Europe as they are in the UK!
When Mr Bieber’s ‘Mistletoe‘ song charted a couple of years I despaired. It was worse than Biff Pilchard’s ‘Mistletoe and Wine‘ (and it messed up every search engine’s responses to the word ‘mistletoe’ for ever!).
News reports this week reveal that Pilchard’s version of Mistletoe and Wine is an over-sentimentalised version of a more politically-motivated original. And the original was part of a 1987 musical version of A Little Match Girl. You can watch a version of that here.
This information is some comfort I suppose. But it did make me wonder – would we ever get a decent mistletoe-themed song at Christmas?
“Father Christmas Do Not Touch Me“. (actually briefly the A-side as they swapped it round in November 1974, just to confuse us).
A classic – but probably politically-unacceptable due to its innuendo and improper suggestiveness these days. If you can’t remember it, here it is….
Confessions of a teenager:I remember discussing the song (and singing it too) at the tender age of 13 and 3 quarters, with my good friend Julian Goodwin (now a respectable member of staff at the School of Engineering & Physical Sciences at Heriot-Watt University – complete with slightly scary picture).
Or how too much mistletoe will suck your tree dry (and stop it fixing carbon too)…
It’s the last weekend of mistletoe management and harvest work before Christmas and I’ve been reviewing the orchards we’ve worked in this season. All have been over-neglected, most of the apple trees are in dire need of proper management and all have had far too much mistletoe on them – which is, of course, why we were in them…
Too much mistletoe in a small tree can be bad news, stressing the tree and eventually contributing to its death. And, sure enough, in all of the orchards we’ve worked in recently there have been some newly deceased, but still standing, trees – all with lots of (equally dead) mistletoe. Which makes what we are doing – cutting out excess mistletoe, both male and female plants, regardless of their marketability – all the more important. We don’t want to lose any more of them. I’ve covered management issues here before – and am still looking for your management experiences on the survey at www.british.mistletoe.org.uk
But exactly how does mistletoe stress the tree? Well, one simple example is transpiration – the term used for the passage of water and gases through a plant. Mistletoes – including our European mistletoe Viscum album – transpire more freely than the host tree, forcing a passage of water through the tree’s vascular system from the roots faster than the tree wants to.
This raises interesting issues for the tree in winter, when most would, as most are deciduous, be naturally leafless and therefore not transpiring at all. But the parasitic mistletoe is evergreen – forcing ongoing transpiration throughout the year. And summertime is a problem too – the mistletoe’s leaves transpire faster than the host’s leaves – and so in dry summers the tree will become water-stressed much more quickly if it has lots of mistletoe on it.
There are relatively few studies of exactly how this phenomenon works for Viscum album on apple trees despite it being generally accepted as a major issue. But experimental studies from other host trees with Viscum album certainly support the idea.
Most research has, curiously, been on Pine hosts. Which might sound a little odd to most people – as our Viscum album is usually only seen on deciduous hosts. But there are subspecies of this mistletoe that will grow on evergreens, and one of them, Viscum album subspecies austriacum is a common feature on pines in some parts of Europe.
Recent papers from Spain (Sangüesa-Barreda, Linares and Camarero 2013) and from Switzerland (Zweifel, Bangerter, Rigling and Sterck 2012) have documented the transpiration impacts of this mistletoe – and they confirm that this is a significant problem.
The Swiss study showed that the mistletoe’s stomata – the adjustable pores that all plants have on their leaves to regulate water and gas exchange – were ‘barely regulated’ and so water loss through the mistletoe leaves was substantial. In an effort to compensate for this water ‘leak’ the infested pine trees closed their own stomata. This helped reduce water loss, but not sufficiently enough – and it had the side effect of reducing carbon dioxide assimilation – a gas the tree needs to photosynthesise and grow. CO2 enters the leaves through the stomata – so closed stomata reduce CO2 uptake.
This is, of course, a double whammy for the pine – reduced water and reduced CO2 supplies – so a real problem for the tree, especially in dry periods. The effect is only serious if there is substantial mistletoe growth – but as mistletoe is spreading more rapidly in the area studied the conclusion is that pine mortality will increase in the area, due to mistletoe spread.
The Spanish study looked at the relationship between mistletoe infestation, intrinsic water use efficiency (iWUE) and the increased atmospheric concentrations of CO2. In theory, because higher CO2 levels mean stomata do not need to open so much, the impacts of closure of host stomata due to mistletoe stress could be offset by there being more CO2 anyway. The study confirmed, like the Swiss one, that mistletoe infestation increased drought-stress in infected trees, but also concluded that ‘rising atmospheric CO2 concentrations cannot compensate for the impacts of drought and mistletoe on tree growth’. Which, to be frank, isn’t surprising.
The overall point of reporting all this? To stress that too much mistletoe, whatever the host, will affect the host’s water and gas exchange, and not in a positive way! Management is needed – especially in smaller hosts like apples.
That shouldn’t put people off growing mistletoe of course –a few growths are unlikely to be a problem. And to reach problem levels your mistletoe growths will need to have been growing for several decades. But if your apple tree looks like these (see right) – you need to do some remedial management – and soon!
(PS There’s a video with some impressively overgrown apple trees in the video on this page... and I’m in it too…)
Refs for those who want to know more….
Roman Zweifel, Sara Bangerter, Andreas Rigling and Frank J. Sterck 2012 Pine and mistletoes: how to live with a leak in the water flow and storage system? Journal of Experimental Botany, Vol. 63, No. 7, pp. 2565–2578, 2012
Gabriel Sangüesa-Barreda, Juan Carlos Linares, J. Julio Camarero 2013 Drought and mistletoe reduce growth and water-use efficiency of Scots pine Forest Ecology and Management 296 (2013) 64–73
Pagans, Wiccans, Druids and Don’t-Knows assembled yesterday for a reassuring mistletoe ceremony in the Severn Vale. The gods (you decide which ones) were kind to us – the weather was beautiful, and only slightly chilly.
I’m posting a few pics of the preparations here. There are none of the actual ceremony (as we were all taking part). Thanks to Keith for hosting it and Caz for organising it.
An 11-year old girl selling mistletoe in Portland (the one in Oregon, not the one in Dorset) may have succeeded in changing the rules at the city’s Saturday Market. Last weekend, after she set up a stall selling mistletoe for $4 a bunch (to raise money for her dental braces) she was told she had to stop, as she hadn’t paid for a stall licence.
Madison Root and her family thought her small operation would be fine, as there are many unlicensed buskers and beggars (‘panhandlers’ in local parlance) active in the market area. But she was told that asking a price, rather than relying on goodwill wasn’t allowed – she could raise money by begging but not from sales!
The resulting publicity led to huge interest in her story, many hundreds of orders, and provision of an alternative sales pitch by a Radio Station. And she’s already raised most of what she needs before evening trying the market pitch again. This video explains in more detail.
Meanwhile the municipal authorities have had to go on the defensive, and are suggesting they might alter the rules to be more flexible in future.
Madison is quoting as saying “It’s not about mistletoe. It’s not about me being kicked out. It’s about all of us, It’s about society accepting begging more than hard work and to set a goal for ourselves.”
But I reckon it’s all about the mistletoe really – which is, after all, a plant species* that symbolises peace, friendship and healing – and isn’t that what she’s achieving?
If you’re in North America you can buy Madison’s mistletoe direct from her website http://madisonsmistletoe.com/ I think she might raise rather more than she expected to…
(*although, of course, Madison’s mistletoe isn’t the original mistletoe species of peace, friendship and healing, as her’s is a North American mistletoe species – but I think we can let that point pass…)
. Commercial break:
But if you’re in the UK you can get the original mistletoe of legend from The English Mistletoe Shop – as well as Grow-Kits, Grow-Kit Gift Cards, Books etc.