Ahhh Biska!

In urban myth Tequila is flavoured by a worm in each bottle. This is, of course, untrue. Only certain types of Mezcal (similar to Tequila) bottles have worms – and even those aren’t worms, they’re moth larvae from the Agave plants that are fermented to make the drink. Not worms, and not in Tequila.

Popular belief will also tell you that mistletoe is toxic, dangerously so. So you might think it’s a myth that there’s a Croatian Brandy flavoured with mistletoe, sometimes with a sprig in each bottle.

But the myth here is about the toxicity not the brandy. Mistletoe is toxic, but not dangerously so. Indeed it is a popular herbal tea across much of Europe. And the brandy – known as Biska – definitely exists.

Until last year I’d never tried it but, just before Christmas 2019, some friends brought me back a bottle from their travels in Croatia (thank you Mark and Klay!). This is it (above and right) carefully posed with some, er, mistletoe (I do like my pictures to have context).

It’s interesting stuff, a little rough perhaps and also cloudy, definitely brandy but with a distinct flavour to it – which is not solely due to mistletoe, herbs are added too.  It reminded me, oddly, of whisky.

This got me thinking about how it is made and what range there might be in manufacturers, so I did a l little research back then, updated recently for this blog.

The first, and most unexpected, issue that came to light is that there may be two mistletoe species involved. White Mistletoe – our familiar evergreen Viscum album – and Yellow Mistletoe, Loranthus europeaus, which occurs in central southern Europe . This differs from Viscum in having yellow berries, regularly growing on oak (rare for Viscum) and – key fact alert – being deciduous.  It doesn’t keep its leaves in winter.

Two mistletoes? This could get confusing. And it does.

Most accounts of Biska stress that it is made with White Mistletoe and added herbs. Which is what I expected. The main centre of Biska production seems to be the tiny town (population just 30 according to wikipedia) of Hum which calls itself ‘the town of Biska’.  Hum has a tradition of making mistletoe brandy, inspired by a historic recipe apparently recorded for posterity by Josip Vidov, a herbalist-priest who lived there. Today the town has a Festival of Rakija (brandy) to promote production of various distilled spirits – with a bewildering variety of flavours including nettle, juniper, sage, lemon balm, spruce, lime, spices, liquorice, herbs and fruit.

If you google Biska you’ll find various brands, most saying it is made with White Mistletoe, and sometimes making interesting claims for its medicinal properties. Presentation and bottle style varies immensely – see some pictures below:

This slideshow requires JavaScript.

The Yellow Mistletoe references are a little harder to spot – but one of the first, spotted last Christmas, was triggered by that bottle brought back from Croatia. The ingredients list label simply says it contains alcohol and mistletoe leaf extract – no identity is given for the mistletoe.  But, on websites listing this particular Biska (e.g. this one), it is described as

“obtained by soaking the leaves of yellow mistletoe (Loranthus europeus) in komovica [a type of brandy].

That seems fairly definitive. Yellow mistletoe!

But a fuller description, on the same website, goes on to list the ingredients as

“komovica brandy, white mistletoe”

A complete contradiction.

So which is it? It’s impossible to say without further information.

It is tempting to suggest that all Biska is made with White Mistletoe and that references to Yellow Mistletoe are errors, or even translation mistakes. After all, White Mistletoe is the evergreen one, and the accounts of making it do suggest the leaves are harvested in winter – when Yellow Mistletoe would have no leaves.

But I suspect there is some use of Yellow, at least for some versions.

Here’s a promotional picture (below), from a website promoting Biska and Hum, that shows a bottle of Biska set amongst some mistletoe sprigs. But those aren’t White Mistletoe sprigs. The leaf shape, leaf positions and branching patterns are all wrong. It is Yellow Mistletoe, Loranthus europeaus.

And here (below) is another contradictory one (from this website), the bottle being promoted against a background of some oak branches complete with Yellow Mistletoe growths across the front of the bottle (though the description, below the pictures, claims the mistletoe is gathered in winter from apple trees – which would be White Mistletoe):

I do wish they would make their minds up about which mistletoe is in which bottle.


For more about mistletoe visit the Mistletoe Pages website.

And if you do want to grow mistletoe why not try a Mistletoe Grow-Kit?  Available from the English Mistletoe Shop website at englishmistletoeshop.co.uk

 

Hanging the Mistletoe, by Dante Gabriel Rossetti

Rossetti’s Hanging the Mistletoe
Rossetti’s initials and date

By the mid-nineteenth century hanging mistletoe at Christmas was all the rage, featuring regularly in accounts of celebrations, particularly newspapers and magazine, often with pictures.  And of course there were paintings too, some by very famous painters – a favourite of mine is Bringing in the Mistletoe, a druid-themed painting by Edward Atkinson Hornel.  But that’s not the one I’m featuring today!

Most were of a much more domestic scenario than Hornel’s picture, and one of the best of these is Hanging the Mistletoe by Dante Gabriel Rossetti, painted in about 1860.  This is it (above left).

This is a really powerful painting, though simple too; a tight composition of a young lady hanging mistletoe and tying it with a red ribbon.  Colours are emphasised by a dark background silhouetting the mistletoe, with berried holly in the foreground and the auburn-haired young lady herself wearing floral sleeves on a sage-green dress.  It is a classic of Rossetti’s later style (late 1850s onwards) described, on the Wikipedia entry about him as “powerful close-up images of women in flat pictorial spaces characterised by dense colour. ”

The painting is generally dated to Christmas 1860 – and indeed this is written on the picture, just below Rossetti’s initial, though some sometimes suggest it might actually have been pointed later.  The picture also has other titles – sometimes described as Girl Tying Up Mistletoe and also as The Farmer’s Daughter.

It was worked up by Rossetti from a chalk drawing – which has also survived (see left).  But this, curiously, is dated December 1868.  The explanation seems to be that this, the drawing, was given by Rossetti to his friend George Boyce, and that Rossetti added the date at the time of the gift, not when the drawing was made.

Rossetti’s portrait of Elizabeth for their marriage in 1860

The date is important because it might help identify the woman in the picture.  Most accounts suggest it is his wife Elizabeth Siddal (1829 – 1862) who married him in May 1860.  She was red-haired and would, surely, be the model for this.  Here (right) is his picture of her at the time of their marriage.  The 1860 date fits and she was already a popular model – many will be more familiar with her as the woman floating in the water in the 1851 Ophelia by Sir John Everett Millais.

Ophelia by Sir John Everett Millais, the model is Elizabeth Siddal who had to lie in a full bath of water for this sitting, which became a problem for her when it got cold.
Rossetti’s painting “Bocca Baciata” dated 1859, featuring Fanny Cornforth
Rossetti’s painting “La Ghirlandata” dated 1871, modelled by Alexa Wilding

There are occasionally other suggestions for the mistletoe lady however – some commentators thinking that it may be Fanny Cornforth (see left) whom Rossetti had been painting from at least 1859 and with whom he had an affair, especially in the years after Elizabeth’s death in 1862. Perhaps the picture is later than 1860 after all?  Though in that case why would Rossetti sign it as 1860?

It also seems possible, if opening up both date and sitter to review, that it could be yet another auburn-haired model, Alexa Wilding (see right), whom Rossetti discovered in 1865.

But it is probably Elizabeth in the mistletoe picture.


For more about mistletoe visit the Mistletoe Pages website.

And if you do want to grow mistletoe why not try a Mistletoe Grow-Kit?  Available from the English Mistletoe Shop website at englishmistletoeshop.co.uk

 

Mistletoe and Orchards on ITV today

Plenty of mistletoe mentions on ITV this morning – all within the 2 hour show Love Your Weekend with Alan Titchmarsh (on ITV Hub here).  Helped along a bit by Sir Cliff ‘Mistletoe and Wine‘ Richard being the main guest.

Christmas swag-making featured about 30 minutes in – with plenty of mistletoe incorporated into a very long decoration.  Some good mentions of how sticky the berries are, and their need for light when germinating, but then Mr Titchmarsh ruined the illusion that, for once, here was a TV Gardener who knew how to grow mistletoe, by stating, categorically, that berries had to be ‘rotten’ before the seeds would germinate.  Where on earth did he get that bit of nonsense from??  Berries have to be mature (which they will be in February/March, not now) but not rotten.   How would being rotten help?!  They germinate best when fresh and healthy.  Yet another TV Gardener getting it wrong (see many previous blogs over many years).  I really do despair.

In mid-flow….

All the more frustrating because I had helped make this programme – their Tree of the Week was Apple, using footage taken in an orchard session with me back in October, with Lesley Joseph’s voiceover referencing the link between apple trees and mistletoe (49 minutes in if you watch it) and then a session with me talking about mistletoe, in that same Gloucestershire orchard, at 76 minutes* in. Nice little bit of film, didn’t realise my hair was getting so grey though!

And, towards the end (about 105 minutes in) another nod to apple trees and Gloucestershire orchards when Alan and Sir Cliff sample some liqueurs, including an Eau de Vie made from apples grown in a heritage varieties orchard in Gloucestershire.

Apples trees, orchards and mistletoe – what’s not to like?  Just incorrect (as usual) TV Gardener advice!

(*timings are all from the 2 hour programme as broadcast.  If you’re watching on ITV Hub it’s 30 minutes shorter (fewer ads) so my bit is at about 59 minutes in.  If watching ad-free on ITV Plus it will, I assume, be even earlier.)


And, Alan, if you’re reading this, if you do want to grow mistletoe why not learn how using a Mistletoe Grow-Kit?  Available from the English Mistletoe Shop website at englishmistletoeshop.co.uk

And for more general mistletoe Information visit the Mistletoe Pages website.

The Mistletoe Boats

Reproduced full size below the text…

Going through old trading accounts of mistletoe ( as I am today, compiling some figures for a research paper) I’m often surprised at the attention given to mistletoe imports, once acknowledged to be the main source of Christmas mistletoe in Britain.  Yes we do grow our own, and do still cut and sell our own, but there was once and probably still is a flourishing trade in imports, mainly from France.

Newspaper coverage of these used to dominate mistletoe stories at Christmas, with comparatively little attention paid to the home-grown stuff.  It’s not clear why this is – whether the imports really did outweigh the home-grown stock so much or whether a boat-load of mistletoe was simply a better story.  So it may have been selective reporting.

Whatever the reason these stories have died down in recent years, with most media attention paid to home-grown mistletoe, especially that sold at the Tenbury Wells Mistletoe Auctions.  This is also selective reporting as there is much sold by other means and a lot still imported.

But getting a complete picture is virtually impossible – not least as there are no trade restrictions and so no need to document imports from France.  This may well, of course, change soon as the UK moves out of the EU transitory arrangements in 3 weeks time!  Almost certainly not for the better.

It’s worth noting that trade tariffs for mistletoe imports are not unprecedented – indeed in the 1930s and 40s there were import licences on most cut flowers including mistletoe.  These were often relaxed seasonally for mistletoe – but sometimes only a week or so before Christmas thereby raising prices up to that point.  Who knows what 2021 will bring??

Much of the newspaper coverage of imports concentrates on simple figures – wowing the reader with tonnages, numbers of mistletoe-filled crates, etc.  But there are occasional longer reports, and some quite hair-raising stories of decks piled high with mistletoe crates.

This cutting is from 17th December 1936, and is written by (or as if by) ‘Mademoiselle Marie’ a French lady travelling by ferry across to England.  It’s a neat account, right down to the detached white berries rolling around the quays and decks, a vision familiar to anyone who has prepared mistletoe in bulk.  [whilst they’re rolling they’re fine, it’s when you tread on them that the fun begins as they stick to your shoes, and later on to the carpet].

Have a read (reproduced full size below); it sums up the whole business in France, when mistletoe was cut deliberately to control it and sold to le britannique crédule for profit.  The only thing I’d query is the mention of the children dressed as guisers in Edinburgh.  Mademoiselle Marie says she’s told ‘guiser’ is derived from Gui, the French for mistletoe.  This seems not only unlikely but at odds with the normal explanation of the term, often used at Halloween these days, as simply a shortened version of disguisers –  i.e children dressing up in costume.


Mistletoe Information: for general mistletoe info visit the Mistletoe Pages website.

And for UK mistletoe books, cards or kits to grow your own mistletoe visit the English Mistletoe Shop website at englishmistletoeshop.co.uk

Whovian mistletoe from 1978

A little light relief from current affairs – for Doctor Who fans anyway.

I’ve commented before on mistletoe having bit parts in Doctor Who – notably protecting Queen Victoria (and David Tennant’s Doctor) from a Werewolf in a 2006 episode.  And also mistletoe featuring, unremarked but possibly significantly, outside a portal in a 2017 episode with Peter Capaldi’s Doctor (I met Mr C briefly this year. Nice man, he said ‘hello’).

Now, via the magic of Britbox, I’ve discovered another whovian mistletoe moment, with Tom Baker’s Doctor, in the 1978 4-parter The Stones of Blood. This story (the 3rd of the Key to Time stories, for the anoraks among us) features a prehistoric stone circle and a back story about druids. And so, inevitably, there’s some mistletoe.

I remember something of this one when it was first broadcast, primarily because I recognised the location used for filming – the Rollright Stones in Oxfordshire.  These were recognisable even though the set designers did tart the circle up a bit, adding fake additional stones, including capstones in Stonehenge style, to the middle. The druid angle seems a strong part of the story at first, with a bevy of druids conducting blood sacrifices, including an attempt on Tom Baker.  The druid theme does, however, peter out in the later episodes.

But what there is is quite entertaining, with the Doctor’s usual comments on personal experiences of times past. In conversation with the lead druid, a Mr De Vries (who, spoiler alert, doesn’t survive long) the Doctor refers to John Aubrey, the antiquarian who did so much to promote druidry in the 17th century. It’s well-known that Aubrey elaborated and re-invented many druidic customs but the Doctor goes further, implying that he knew Aubrey and that druidry was ‘founded by him as a joke, he had a great sense of humour did John Aubrey’!

Mistletoe features only in passing. Before the Doctor is trussed up and tied to a stone we see Mr De Vries performing a ceremony indoors with mistletoe on an alter. The screenshots I’ve got are low quality but you can see, I hope, that it is, er, plastic mistletoe. Which is slightly disappointing, I’d wager that even John Aubrey would disapprove!

This slideshow requires JavaScript.

Another berry good year

Loads of berries, again, on the mistletoe this year.

Which would, normally, mean lots of harvesting, sales and, of course, use of mistletoe.

But we have two problems this season, already mentioned in recent posts, both caused by the Covid pandemic.  Firstly fewer mistletoe sales – the Tenbury Wells Auctions are cancelled.  And secondly social distancing – how can you kiss under mistletoe when you can’t get closer than 2 metres and wearing a mask?

A flurry of media interest in both these problems this week – in the tabloids (Daily Star on Tuesday, The Sun today) and on the telly (Sky News yesterday).  You might think it’s yet another doom’n’gloom story and it is for some – certainly those sellers and buyers who use the Tenbury Auctions.  And it is tragic for Tenbury Wells itself – losing one of its main attractions this year.  The many other mistletoe suppliers (direct wholesale sellers and online retail sellers) may be finding themselves rather busy as there will be more demand from them.  Assuming people actually want mistletoe of course – there will be reduced demand from commercial venues at least.

But there is some humour to be had – at least concerning how to kiss, or not, under mistletoe during a pandemic.  The Star billed it as Snog Off, Sky News as Kissless Christmas and my suggestion of mistletoe elbow-bumping instead does make people laugh (even though I’m quite serious about it…).  The Star had that on the front page as Elbow Bump under the Mistletoe Anyone? And Sky News were just happy I’d cheered them up with elbow bumps, and mistletoe air-kissing through a mask at 2 metres, after a long session of depressing mainstream stories.

The Sun’s online story (I haven’t seen the print edition yet) today claims that they’ve asked Downing Street whether there will be a mistletoe ban!  And reckons they got this answer:

The PM’s spokesperson said that the Government would not seek to ban the popular Christmas treat over fears that people won’t stick to social distancing.

So, that’s alright then.  Phew!

Mistletoe auctions covid-cancelled

Just a quick update re the Tenbury Wells Mistletoe Auctions – these have now also been cancelled, as well as the Mistletoe Festival.

Which seems to raise the possibility that, not only will there be no kissing under mistletoe because of Covid fears, there’ll be no mistletoe to kiss under either!

Never fear, not all mistletoe comes from Tenbury’s auctions!

There are many other ways for wholesalers, retailers and the public to buy mistletoe – it’s just that Tenbury is the best-known and most visible source.

I’ll post about some of the other ways soon….  

Mistletoe Season 2020 – this year with added Covid…

gasmaskmistletoephotoSo here we go again, another mistletoe season on the horizon.  But can mistletoe work its magic with Covid-19 restrictions?  Will kissing a stranger be a possibility this season?  Is a quick snog with a friend achievable? We shall see. Though I think I can predict much of the answer already!

But whatever happens I’m fairly confident people will still be celebrating with and hanging up mistletoe.  Even if those mistletoe kisses end up being reduced to mistletoe elbow bumps or mistletoe foot foot waggling.  It could be interesting.  And it’s the concept that counts – and this year the kissing may well be only conceptual.

Mistletoe events this year are, not surprisingly, fewer than normal.  Nearly all my own bookings for evening events have been cancelled and I’m expecting the remaining ones to be closed soon .

And the Tenbury Wells Mistletoe Festival has been cancelled too.  As have many other mistletoe-themed events up and down the country.

The Mistletoe Auctions at Tenbury Wells are still on – this year on Tuesdays 24th November and Tuesday 1st December.  Details of those at https://nickchampion.co.uk/auctions/holly-and-mistletoe/

And mistletoe commerce online is continuing too – for instance we’re now open for Mistletoe Grow-Kit and Gift Card orders at the English Mistletoe Shop.

So all is not lost – and I’ll be blogging about mistletoe on and off through the season.  I’m also working on two formal papers reviewing mistletoe in Britain – and will report on progress of those as they develop.  More soon….

A back garden parasitic plant safari

Parasites in lockdown – a round-up of the parasitic plants I’m growing in our garden this year, so far: Not just mistletoe, but also dodders (two species), broomrape (one species – another due soon) and yellow rattle. And an aspiration for Lousewort and a hope of Toothworts (two).

mistletoe shoots 2020Firstly mistletoe, obviously. There’s lots of that (I wonder why?!). These are young growths, about 4 or 5 years old, planted by Blackcaps on an already mistletoe-laden apple. Looking particularly splendid at the moment with the new lighter-green shoots and leaves.

yellow rattle young shoots 2020A bit more down to earth – Yellow Rattle, Rhinanthus minor, a root parasite of grasses, growing here in a pot amongst greater quaking grass Briza maxima. Yellow Rattle is, like mistletoe, only a hemi-parasite as it has its own green leaves, linking, in this case, to the host grasses via the roots. Pretty flowers in summer – these are only young shoots.

orobanche shoots 2020 aVery down to earth – emerging flowering shoots of Ivy Broomrape, Orobanche hederae, at the base of some ivy in a pot. It’s a full parasite – no chlorophyll of its own – that parasitises ivy roots.  Fairly easy to grow – I’ve been growing this for many years now – but unpredictable year to year – these are the only visible shoots from several previous locations (and ivy-filled pots) round the garden that we have this year. They’ll be 6 inches or more high when they’ve fully grown – unless the slugs and snails get to them first. Which they sometimes do.  Will be trying some more Orobanches later this year…

nettle dodder 2020Up in the air again – this is Greater Dodder, Cuscuta europaea, which parasitises nettle stems by winding round them and linking into the host vascular system. No leaves, so these are fully parasitic, unlike mistletoe. They germinate in soil but become detached from the ground once they’ve reached a host stem. Nettle is the nominal host but they will twirl and link to any plant within reach later on – they seem to really like the Epilobium stem nearby (see pic). This is my second season of growing these – including on the stingless form of stinging nettle, Urtica dioica subsp. galeopsifolia, which is slightly more garden- and human- friendly.

gorse dodder shoots 2020And, a first for us for 2020, another dodder – Cuscuta epithymum – smaller than the nettle one but more familiar to most as the pink stems that festoon and parastise gorse on moorland in the summer. These are, so far, tiny seedlings from seed I (and John Hollier) gathered in north Devon last summer. I’m trying them in pots of gorse – only a few have reached the host stems so far, and where they have done this the tiny white and yellow parasite seedlings are just beginning to grasp the hosts. They’re a long way from those massive pink growths of late summer.

lousewort 2020And, to represent some missing parasites, here’s a pic of some rather dry-looking Lousewort, Pedicularis sylvatica, taken this week not in the garden but up a hill in West Devon (despite the lockdown – we are allowed a bit of exercise!). It normally likes it marshier than this so it isn’t very happy! A similar concept to Yellow Rattle, parasiting roots.

Hoping to grow this next year – and also hoping to get some progress with the Toothworts – common and purple – neither of which I’ve had success with, yet…

Mistletoe in May, and Maths (and pandemics)

May Day! Summer will be here soon.  And mistletoe is doing fine, just keeping on growing.  My first picture here is, literally, mistletoe in May – a small mistletoe growth growing low on a May (Hawthorn) tree in full blossom.  Taken in late April actually – on the banks of the Severn near Framilode earlier this week.  Hawthorn/May is one of mistletoe’s favourite hosts, though the growths are often rather small and mis-formed compared to the spectacular mistletoes of larger trees (the one pictured is certainly rather deformed!).

And how does mistletoe behave in May (the month, not the tree)?  Is it ‘just growing’ as I suggested in my last blog entry  – or can more be said?  What sort of growth is it?

Well… with the current worrying about when Covid-19 lockdown might be relaxed and how the mysterious ‘R’ number has to be satisfactory beforehand I thought a brief comparison with mistletoe might be interesting.  The ‘R’ number is a factor in the rate of disease spread – and is just as relevant to mistletoe as it is to SARS-CoV-2 (the coronavirus that causes Covid-19).

Mistletoe, like SARS-CoV-2, can be considered a pathogen – in this case infecting a host plant – and so the R number concept applies perfectly.  Especially so for our mistletoe (Viscum album) as this mistletoe species does have a very distinctive growth and spread pattern mathematically – in theory at least.

Current media articles (e.g this from the Guardian) are making the point that if R is more than 1 the disease will continue to spread, and spread will be much faster the higher the value. If less than 1 it will decline. The R value is the number of people an infected person will pass the disease on to.  Current efforts seem to have changed R from 3 to about 0.7 in the UK in the last 6 weeks or so.

This has parallels with several aspects of mistletoe growth – though for mistletoe the factor is much more definable and fixed.  And it can be clearly seen now, in May.  Every branch from last year, tipped with a pair of leaves and small flowers (which opened – and closed – in Feb/March) is now producing two new shoots, each one tipped with a new pair of leaves and, between them, a small bud which will be next year’s flowers.  This picture (right) taken this morning shows this clearly.

So, just looking at those leaves to start with, we have a shoot topped with a pair of leaves which is becoming two shoots each topped with a pair of leaves.  Later in the summer last year’s leaf pair will drop off and these two new shoots will become the tip of the plant – the only part with leavesAnd there will twice as many leaves as last year. That is a factor of 2 each year – which suggests an exponential growth rate.  Every shoot (with one pair of leaves) produces two new shoots (each with one pair of leaves) every year.

R is therefore 2 for each pair of leaves.  One pair of leaves becomes two pairs in year 1, 4 pairs in year 2, 8 pairs in year 3, 16 pairs in year 4 and so on.

Such a precise growth pattern is unusual and is one of things that makes our mistletoe, Viscum album, so special.

This is very definitely exponential growth – and it can (of course!) be represented by the formula

y = abn

where a is the original number of shoots/pairs of leaves, b is the factor (the R number) and n is the number of years.  y is the number of pairs of leaves after n years.

So… for year 4, substituting in the values a = 1, b = 2 and n = 4:

y = abn

y = 1 x 24

y = 16
(as already calculated above)

If you know your maths you’ll already be thinking that these numbers could get very large very quickly after a few more years – and you’d be right.  Think about, say, year 10 for example:

y = 1 x 210

y = 1024

That’s 1024 pairs of leaves at 10 years, all from just one pair at the start.

If the exponential formula y =1 x 2n is plotted as a graph you can see the full effect (formula simplified to y = 2n or, on the graphs below, to y = 2x):

 


The left hand graph shows the exponential growth shooting off the scale at about 1400 leaf pairs at about 11 years.  The right hand one is zoomed out showing it going off the scale again, this time at 150000 leaf pairs at just over 17 years.   That’s a lot of leaves.

And that number is extremely important if you think of mistletoe as a pathogen.  Each mistletoe leaf transpires water in a different, more reckless, way than the host tree’s leaves.  The more mistletoe leaves there are the more water-stressed the host becomes.  Doubling each year doubles that impact.  So it can matter quite a lot.  One of the key needs when managing excess mistletoe is simply to cut off the leaves – which, in theory at least, can reduce water stress very effectively.

But how real is all this – this is just a very simple mathematical model – albeit based on observed growth patterns. What happens in reality?  Is it better or worse?

Well it depends – on whether the mistletoe is managed, how high it is the tree and how wind-damaged it gets (branches break off very easily), whether it is cut for Christmas, whether it gets diseased (mistletoe gets diseases too) and whether leaves are grazed or damaged by birds or invertebrates.  So the number is likely to be less in reality.  (Except, of course, for the instances when a shoot produces 4 shoots and 4 pairs of leaves – but that’s another story…)

Still with me?  Good, there’s a little way to go yet….

So far this has been about one mistletoe plant – but the real virus comparison should be with mistletoe spread and new infections…  Either on other branches of the same tree or to adjoining trees.

And for this exactly the same maths applies – since spread is all to do with how many seeds mistletoe produces, and that relates to how many berries develop, which relates to how many flowers and so how many flower buds.  And the flower buds are between the pairs of leaves.  So it is absolutely the same maths – each pair of leaves has one set of flower buds.  And so each pair of leaves has a direct relationship with the number of berries and seeds produced.  The seeds are the mistletoe’s equivalent of the virus.  And, with 3 -5 flowers per bud and so 3-5 berries/seeds per bud, it is a lot of seeds.

So… the number of seeds, in this simple model, increase in the same ways as the leaf pairs.  Numbers way off the scale after only a decade or so.  Which would suggest mistletoe might spread very fast – with all those seeds.

Except that it doesn’t – it spreads very slowly.

Perhaps the model is even less like reality for the seeds?  There are certainly many extra factors to consider – some positive factors some negative.  On the positive side (more seeds) there is the factor of the overlooked flowers – it is a simplification to say flowers are only between the leaf pairs – there are usually many in the stem axils immediately below the leaf pairs too – so the model is under-estimating the potential of flowers/berries/seeds, possibly by quite a big factor.

On the negative side (fewer seeds, or fewer effective seeds) the first, most obvious issue is whether the flowers are pollinated or not –  if not then they won’t form berries and so won’t produce seeds.  And since they rely on insect pollination in February and March – which can be a challenge in cold years – pollination can be variable.

Another obvious factor is considering how many seeds, however perfectly produced, will ever get a chance to germinate on a tree branch – and this very much depends on how well they are spread by birds – and by which birds.  Mistletoe is not liked by most and even those which do eat the berries often only take them in small numbers if other berries are plentiful.  So the seeds may not get spread, or not spread efficiently.   See, for example, these berries, photographed (left) this morning, which are still attached to the parent plant – the seeds in these will never get a chance to grow now.

So, numbers of flower buds doesn’t equal number of berries and number of berries/seeds produced does not equate to numbers of infections.

Nonetheless there is still a massive increase in berry production as a female mistletoe plant matures – and so the older the mistletoe is the more likely it is that there will be spread to adjoining branches or trees.  As regular mistletoe blog readers will know there are also some interesting changes in how mistletoe is spread, larger numbers of overwintering Blackcap birds meaning more efficient spread tree to tree.  Fascinating stuff – and difficult to quantify.

Meanwhile, if you’re growing mistletoe in your garden and are worried by any of the above don’t be (unless you have masses left unmanaged for decades!).  Small to medium mistletoe growths are not a problem and will only become one if left unmanaged, just like most other garden plants.  Look after your mistletoe and, once it’s 10 years old or so, prune it back now and then to adjust that ‘R’ number to a level that’s right for you.