Mistletoe Auction Time

trading6The first Mistletoe Auction of the year takes place tomorrow morning, which to many means the proper start of the mistletoe season.

The auctions are run by Nick Champion and are held at at Burford House Garden Centre, Burford, Tenbury Wells, WR15 8HQ.  Details on Nick’s website nickchampion.co.uk but shortcut for buyers is nickchampion.co.uk/site/assets/files/1015/buyers_information_2021.pdf and for sellers (too late for tomorrow now but there’s another next week!) is nickchampion.co.uk/site/assets/files/1015/sellers_information_2021.pdf.

IMG_20211122_145853The berries are already nice and white – and  there’ll be more mistletoe news here soon.

It’ll be mistletoe time again soon

With just a few days until October, we’re yet again at the start of the mistletoe season. So it is perhaps time for a quick review of how things are looking this time round:

As is fairly usual these days, there’s a reasonable crop of berries forming, so it could be another good year for quality mistletoe. This seems to be the norm, and indeed there is research that suggests berry numbers per branch don’t, often, change much from year to year.

mtoe27thsept2021This might seem surprising – but, assuming pollination is successful, shouldn’t be when you consider how the plant grows. Each branch divides into two exactly once a year and each of those two new branches has identical terminal flower buds, every year. So there shouldn’t, logically, be much alteration in number of flowers, for any given section of branch, year on year, as the pattern and number of flower buds stays exactly the same. The main variant will be the amount of insect pollination of each flower in February/March and in the mild winters we get these days insect availability, for this essential role is, it seems, always sufficient.

There are other variables in ‘quality’ of course such as the green-ness of the leaves (many plants are yellowy-green and of less value even with berries) and the legginess of the branches (compact short internodes seem more attractive) and whether male mistletoe (which never has berries) has been mixed in with the female.

All of this is relevant to mistletoe sales, the most well-known of which are the auctions at Tenbury Wells, cancelled last year because of the pandemic. There was, at that time, much talk of mistletoe shortages as a result, but my impression was the reality was different, and there was still plenty of mistletoe to be had. This does highlight the fact that, contrary to popular belief (especially in the media), the Tenbury auctions are not the only way to trade mistletoe! Indeed most of what’s seen in supermarkets and greengrocers may not be from Tenbury at all, and might not even be of British origin. Imports of mistletoe from mainland Europe have been significant since the late 19th century. It’s not all about Tenbury.

That last point might imply new and different trouble ahead – because the UK has left the EU trading bloc. Last autumn the UK was still in the ‘transition period’, not actually in the EU but still with freedom of trade. That ended in January 2021 and new rules on trade are now in place – or would be if the Government didn’t keep kicking them into the long grass rather than tackling the problem they’ve made.

For cut mistletoe, assuming it is classified as a cut flower, the rules are, at first sight, simple. Cut flowers originating in the EU have a zero-rated import tariff, so basic prices should not go up (though 8% tariffs were expected at one point in the discussions). That sounds good, but it’s not quite that simple, as there is still paperwork that wasn’t needed before – customs forms etc. This requires more work, adds more cost and reduces the attractiveness of the trade.

The paperwork might get very onerous if phytosanitary certification is needed. Leaving the EU means that the UK is now longer in the same phytosanitary area and imports and exports of plants or plant parts, may need such certification*. Indeed this was, and still is, the plan for cut flowers, with phytosanitary inspections due to have started last April. Happily, for this Christmas season at least, this isn’t yet needed, as the deadline for starting inspections of cut flowers has, like many other deadlines, been extended, in this case to January 2022.

So there will, in theory, be no major barrier for mistletoe imported from EU countries this season. But I wouldn’t be surprised if less is sent, as the rules, and the constant changing of dates, can be very confusing. This isn’t new, there were trading tariffs and restrictions on mistletoe at many times in the past 100-150 years, but there have been none in recent decades, none in living memory for most traders.

reduced_res_IMG_3776Meanwhile, back at Tenbury Wells, business is, everyone hopes, back to normal this season. Auctions are planned for Tuesday 23rd November and Tuesday 30th November. Run, as usual, by Nick Champion: https://nickchampion.co.uk/auctions/holly-and-mistletoe/


gyo*PS The need for phytosanitary certification is definitely interfering with some aspects of the mistletoe trade. The Grow-Kits marketed by the English Mistletoe Shop for example, like most products sent as seeds for growing, can no longer be sent to the EU or even, at present, Northern Ireland, without individual inspection of each by a UK government inspector, with significant cost each time. There’s no suggestion that they would fail the inspection, but the additional time and cost involves simply makes the process non-viable.

A tale of two mistletoes

There’s a new mistletoe species here at Mistletoe Towers, all the way from Africa originally.  Though this particular set of seeds came from, er, Malvern. 

One seedling germinating
on Euphorbia

It is Viscum minimum, related to our familiar Viscum album, but, as the name suggests, a much reduced plant.  Tiny actually.

I haven’t ever grown it before, though have seen several specimens grown indoors.  For it isn’t an outdoor species, not here in Europe, as its hosts are tropical succulents.   Euphorbias in fact, themselves related to the familiar milky-juiced plants of gardens and woodlands.   In Africa succulent Euphorbias occupy a similar niche to the cacti of North America.  Thick-stemmed, often rounded, plants with minimal leaves, adapted for life in very dry conditions.  They are often mistaken for cacti.

V.minimum, also succulent and minimally-leaved, is a wonderful example of how the mistletoes are adapted to a huge range of hosts.  It lives within the tissue of the Euphorbia, with minuscule succulent leaves of its own, on the host surface.  The biggest features are the flowers, followed by red berries, also close to the host surface.

My plants are, at present, simply germinating seeds, not much to look at yet. Only time will tell if they get established.  So far they look, not surprisingly, very similar to Viscum album seedlings (see pic of one of those on the right).  They are nearly 2 months old now and there are three that look promising.  But none have yet established a hold fast on the host, so nothing is yet certain.

The pictures below show two completely different Euphorbias on which Viscum minimum seeds have been placed.  There are close-ups of the germinating seeds.  Note how much the two Euphorbias have grown in the 2 months I’ve had them.  Much faster growing than cacti.  Though they haven’t been slowed down by the mistletoe yet…

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.

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.

Spring – mistletoe has nothing to do but grow…  

April, in lockdown, and the main mistletoe action season is over – berries ripened (Nov/Dec/Jan), seeds planted (Feb/March), flowers over (Feb/March), pollination done (Feb/March).

From now until next winter mistletoe has nothing to do but grow.  For the seedlings it’s a bit more challenging – they still have to link into their new host’s vascular system, but for a mature mistletoe there really isn’t anything else to do now.  Just grow new shoots and new leaves and, for the female plants, slowly develop the berries over the next 9+months.

This pattern dictates the year for a mistletoe specialist like me – once April comes the talks have finished, the enquiries dry up and we stop sending out grow-kit orders. Time to take stock.  Especially this year as we’re in lockdown because of coronavirus.

This is a time for other plant parasites though, so I may post some news about those soon – dodders, broomrapes, toothworts – this is the start of their time for germination and flowering.

Not forgetting mistletoe though, obviously, so here are a few pictures of the orchard at Standish Court, taken yesterday, showing apple trees festooned with mistletoe.  Too much mistletoe actually – you’ll see in some pics some trees have been blown down, possibly weakened and top heavy due to mistletoe.  The standing tree with most mistletoe is, I’d suggest, doomed unless urgent remedial action is taken to strip off most of the mistletoe.  A few mistletoe growths are fine – indeed I encourage it in moderation – but this many growths mean the tree’s not able to produce enough leaves to keep itself alive (the mistletoe leaves give nothing to the tree) and it will, sadly, die.

Note, by the way, that the trees in blossom are pears, which bloom earlier than apple.  Mistletoe dislikes pears but loves apples, so there’s a marked contrast at this time of year – pears are all in blossom, apples are not – but, in this orchard at least, they are covered in mistletoe.

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Not a mistletoe#1: not even a parasite

Viscum album – mistletoe – showing branching pattern

(the first of some blogs about mistletoe-themed plants)

The distinctive geometric branching of Viscum album, the classic mistletoe of legend, is one of its most distinguishing features. Each branch bifurcates once a year, creating an intricate pattern. Not all mistletoes have this property – for example the Phoradendron species used at Christmas in the US don’t – they look really quite ordinary, not like the European plant at all.

Mistletoe Cactus – Rhipsalis baccifera

But a few other plants do have a similar pattern – though they aren’t mistletoe. The best-known of these are, perhaps, species of Rhipsalis the so-called ‘Mistletoe Cacti’.

Mistletoe Cactus with fruit

There are about 35 species of Rhipsalis, all true cacti with leaves reduced to spines and thick photosynthetic stems, some flattened but some cylindrical.  It is the cylindrical-stemmed ones that are known as the mistletoe cacti as these stems, when they divide, seem to echo the growth of our mistletoe Viscum album.  Their fruits even look vaguely like mistletoe berries.

These are ‘jungle cacti’ from Central and South America, with several forms and species popular as house plants.  Some are quite ‘hairy’ with fine spines coating the stems but others are virtually spine free. One of the commonest seen is Rhipsalis baccifera which, in its baldest, most spine/hairless form, is quite distinctive.

Some other Rhipsalis species

They are easily grown from stem fragments, though these take a while to root.  Here (below) is my current specimen, grown from three tiny stem fragments I picked up from the ground underneath a neglected garden centre specimen some months ago (I know a bargain when I spot one!)

No flowers yet, so no berries, but it’s now growing rapidly so I hope for some soon next year…

 

Growing your own, for the common good, in NZ

My recent post about the new mistletoe-eating bird in Borneo reminded me of several other exotic (to us in Britain) mistletoe stories. One particular story from last year came to mind – a project in New Zealand where local residents were being given mistletoe seeds in an effort to re-establish local mistletoe species.

NZ mistletoe berries collected for the project

The project, based in Christchurch, involved the collection of seeds by local ecologists and then the doling out of 20 seeds each to local volunteers, for them to plant onto suitable hosts, especially in gardens.  Participants were asked to monitor their seeds to assess success, or failure.

It’s a curious concept – but one which has echoes over here – I’ve worked with many UK conservation groups trying to get mistletoe established in parks and nature reserves –mainly in the east of England, where our mistletoe is relatively uncommon.  Including some very well-known parks and a few palace gardens.  And of course I’ve been involved in garden mistletoe plantings for many years, both directly and through provision of mistletoe grow-kits online.

The trick, which will probably apply to NZ as well as UK mistletoe, is to remember where (i.e which branch, and whereabouts on the branch) you planted the seeds and to be patient, as initial growth is slow and it may be several years before you get a growth of any size.  I’ve lost count of the number of people who write to me, several years after planting, saying they are astonished to find their mistletoe is growing – they assumed, because they had overlooked the initial small growths, that they had failed, but actually they’d been very successful.

I’m not sure how quickly those NZ species grow – but having looked up the story again I see that 2018 was the second year of the project – I wonder whether that’s a reflection of the same problem, establishment after just one year is difficult to assess, so people try again. Although, on reading the news story published in 2018 it seems that 200 new plants had been recorded as established the year before, so perhaps those NZ species establish more quickly than ours!

The Christchurch project was led by Kristina Macdonald, an ecologist with Christchurch City Council – there’s a video with her explaining the project below.  Note that she stresses the value of the plant for gardens – both as an attractive plant and as a resource for other species.  For info on the original 2017 initiative click here and for the 2018 follow-up click here.  As far as I’m aware this project is now completed.


You don’t have to be in NZ to grow mistletoe in your garden.

Try it in the UK with a Mistletoe Grow-Kit from the English Mistletoe Shop

Details at  https://englishmistletoeshop.co.uk