From an ecological point of view there are at least 3 reasons:

• Honeybees have evolved in tandem with certain flowers and they have adapted to facilitate each other;
• One bee is able to rapidly communicate the location of a pollen/nectar source to the whole hive and an army sets out;
• The bees then concentrate faithfully on that flower species until the pollen runs out or the nectar dries up, at which point the job of pollination is accomplished.

These features obviously make the honey bee important from an agricultural/commercial point of view. In addition, hives of bees are mobile and can be moved from crop to crop – an arrangement which can suit bees, farmers and beekeepers so long as everyone has a bit of respect. Wouldn’t that be great?

But some detail:

Evolution

In the beginning there was the wind…

The earliest seed-bearing plants were randomly pollinated by wind-borne pollen which would be caught on droplets of a sticky exudation oozing from their ovules. Because of the hit and miss nature of this method of pollination massive amounts of pollen need to be produced in the hope that at least some of it will find its mark. This method is still used by conifers.

Then came the insects…

It is thought that eventually sap-sucking or resin-browsing insects were drawn to dine on the exudation. The effects of this were beneficial to both parties – the insects were introduced to pollen as a  new source of protein and as they moved around from plant to plant they carried pollen with them and pollinated as they went. Plants pollinated in this way needed to produce less pollen than those still relying on the wind. Insect pollination was also more efficient so these plants were able to produce more offspring and the trait persisted.

Co-evolution

As long as such associations are mutually beneficial, their continuance is at least assured and there may even be further co-evolution. Each step along the co-evolutionary pathway creates a more fruitful relationship although things are more prone to disaster.

Over-dependency

Occasionally a plant may devise an almost perfect method of manipulating an insect for pollination purposes but such cases are so complex they tend to involve a single species of insect. One of the best examples of this is the flower of the orchid Ophrys speculum which looks enough like the female of a certain bee species (not Apis mellifera) to entice pollen coated male bees to mate with it and thus pollinate it in a novel way. While this may be a highly successful method of pollination, the future of the orchid becomes tied in very closely to that of the bee; if the bee species should decline or even become extinct, perhaps due to habitat destruction or a surfeit of exhausted males, then the orchid will be doomed to follow.

Honey bee adaptations

The honey bee has not yet been so tightly hemmed in by co-evolution and they remain relatively broad spectrum pollinators. However they have evolved certain adaptations that suit them for their job such as tube-like mouthparts for reaching down into the throats of flowers in search of nectar and the hairy body which is the ideal surface to which pollen grains will easily cling. There are also pollen baskets but these are designed not for the passing on of pollen but to collect the bee’s share to take home to the hive.

Bee flower adaptations

Plants, for their part, have adapted their flowers to attract bees – all sorts of bees. They tend to have  brightly coloured petals, usually blue or yellow, with a landing platform of some sort. The petal markings may include honey guides which are designed to tell the bee where the nectar is. The nectaries are tucked away near the base of the corolla tube, where only the tube-like mouth-parts of a bee can reach and inaccessible to the chewing of beetles.

There are also cunning floral booby traps designed to manipulate the insect pollinators:

• Scotch broom – Cytisus scoparius  is spring-loaded to burst open when a bee lands, the curved stamens and stigma arching over the bee; the stamens to press pollen onto its back and the stigma hoping to pick up some suitable pollen placed there by another broom plant.
• Gorse (Ulex europaeus) is also spring loaded but in this case the stigma and stamens burst from the floor of the flower, hoisting the bee into the air. Here the target must be the bee’s belly.

• Rosemary officinalis is not sprung, but has stamen and stigma strategically arranged to arch out of the upper part of the flower in such a way as to brush the bee’s back.
• Himalayan balsam or Impatiens glandulifera has stamens situated above the entrance of the flower so as the bee pushes its way in – a streak of white pollen is plastered onto its thorax

• Meadow sage or Salvia pratensis has a carefully placed foot-plate which is hinged to the stamens, when the bee treads on the foot-plate the stamens swing down from the roof of the flower stamping pollen onto its back.  The stigma, meanwhile, extends from the upper lobe of the flower and lengthens with age so that bees entering an older flower brush against it on the way in so delivering the pollen. Presumably this age-related lengthening is a mechanism to avoid self pollination. Click this fabulous photo below for a close up of Salvia pratensis pollination in action – not mine and not a honey bee – all credits to Wikimedia.org

So a day in the life of a honeybee can be quite a circus, hoisted into the air one minute and thumped on the back the next.

Honey bee exclusion

Some flowers have evolved to exclude honeybees in favour of other insects.

A common method of exclusion is by having corolla tubes too deep for the bees’ elongated mouthparts and these are butterfly flowers. An example would be honeysuckle (Lonicera periclymenum).  Unimaginative though – don’t you think? How about weight activated trapdoors, ejector seats or that old favourite – a boxing glove on a spring.

However, exclusion can backfire. Some insects are clever enough to chew a hole into the corolla tube to access the nectaries bypassing the pollination step altogether. Honey bees will sometimes use these access holes too.

Another exclusion method is an open door policy. Primitive flowers such as composites (daisy-like flowers) are open to all and sundry. These are little visited by honeybees as they are not mixers by nature and dislike competition.

Wild carrot (Daucus carota) flowers are white composites but they sometimes have one small red flower in the centre (above).This is thought to attract flies who think the little red dot is another fly and flies are great mixers. Just look at horse muck!

Communication

The foraging force of any one hive may number 25 thousand and they will cover the area within a radius of 3 miles from the hive  in search of nectar and pollen. When they find a good source, they become very purposeful, they load up with pollen and/or nectar, then they go back home to the hive. Once home they will hand out samples of what they have found and dance enthusiastically to tell everyone where it came from – how far, how much and which direction. Bees that respond to the dance and go out and find the source are said to be ‘recruited’. For bees, this means they will go out after this species of flower until either they die or the source does. Communication means that a chance discovery by one bee will lead to thousands and thousands following on and obviously the more bees the quicker will be the pollination.

Good Youtube video on dancing bees here:

Fidelity

The fidelity bees show for a single species helps pollination in several different ways.

• Once they have been discovered by the bees, increasing numbers of bees are recruited to forage on that species moving from flower to flower depositing pollen as they go.
• They will continue to visit until either the nectar dries up or the weather changes. They make the most of spells of good weather.
• When the bees return to the hive they all tumble around together in the hive, passing pollen from bee to bee as they brush shoulders. This increases the likelihood of cross pollination as bees will then be carrying pollen from several individuals of the same species.
• Focussed attention means plants need not produce so much pollen.

Mobility

From a commercial/agricultural point of view, hives of bees can easily be moved from crop to crop where all of the above apply. Bees are regularly employed to pollinate crops of oil seed rape, borage (star flower) and top fruit in the UK.

Meanwhile in the USA, fruit farmers and beekeepers have evolved a highly efficient annual migratory existence following a variety of crops west to east by the truckload across the country. They are paid for their services as pollinators and of course there is the honey too. Crops they are paid to pollinate include apples and pears, cherries and almonds, melons, cucumbers and squash, cranberries and sunflowers. For honey there are orange blossom, alfalfa, California buckwheat, blueberries, Brazilian pepper, palmetto, basswood, clover and gallberry to choose from.

It could be said that they have, between them, created a specialist relationship like the delicate orchid/bee example above. One that is very focussed and even efficient but also very vulnerable and we’ve seen what can happen with the disastrous Colony Collapse Disorder.

Here in Ireland, while farmers will welcome beekeepers onto their land when they are growing oilseed rape or apples etc there are few who will pay the beekeeper to move.

But read on…

The Future

The drive towards increasingly intensive agriculture is accelerating. Each year, more hedgerows and patches of scrub are ruthlessly wiped off the landscape and mixed meadows  reseeded with rye grass. Habitat destruction causes the extinction of wild pollinators and this may lead to an increase in demand for mobile beekeepers here but we should know where that stuff leads.

But always look on the bright side of life – that’s my motto!

Click here for the mechanics of Pollination

Click here for more on Gorse Pollination

Click here for more about Himalayan Balsam

Click here for Ireland’s Pollinator Plan 2015-2020

Sources

Attenborough,D.  Life on Earth – A Natural History. BBC, William Collins and Reader’s Digest. 1979.

Campbell,N.A.  Biology – Second Edition. The Benjamin Cummings Publishing Company Inc. USA. 1990.

Mairson,A.  America’s Beekeepers – Hives for Hire. In National Geographic Vol. 183 No. 5. 1993.

Raven,P.H., Evert,R.F. & Eichhorn,S.E.  Biology of Plants. Worth Publishers Inc., New York. USA. 1986.

Copyright © Beespoke.info, 2016.  All Rights Reserved.

Irish Natives are in green.

Click the table below for a close up then let me know if I’ve missed any:

Click here for February Bee Flowers

Click here for March Bee Flowers

Click here for April Bee Flowers

Click here for May Bee Flowers

Click here for June Bee Flowers

Click here for July Bee Flowers

Click here for September Bee Flowers

Click here for October Bee Flowers

Click here for November Bee Flowers

Click here for a general seasonal guide to important bee flowers

Click here for photos of pollen load colours

Click here for Heathering

Click here for Heather Ecosystem

Click here for how to take a crop of Heather Honey

Click here for Bee Trees: Lime

Copyright © Beespoke.info, 2016.  All Rights Reserved.

Irish Natives are in green.

Click the table for a close up then let me know if I’ve missed any:

Click here for February Bee Flowers

Click here for March Bee Flowers

Click here for April Bee Flowers

Click here for May Bee Flowers

Click here for June Bee Flowers

Click here for August Bee Flowers

Click here for September Bee Flowers

Click here for October Bee Flowers

Click here for November Bee Flowers

Click here for a general seasonal guide to important bee flowers

Click here for photos of pollen load colours

Click here for Heathering

Click here for Heather Ecosystem

Click here for how to take a crop of Heather Honey

Click here for Bee Trees: Lime

Copyright © Beespoke.info, 2016.  All Rights Reserved.

Irish Natives are in green.

Click the table for a close up then let me know if I’ve missed any:

Click here for February Bee Flowers

Click here for March Bee Flowers

Click here for April Bee Flowers

Click here for May Bee Flowers

Click here for July Bee Flowers

Click here for August Bee Flowers

Click here for September Bee Flowers

Click here for October Bee Flowers

Click here for November Bee Flowers

Click here for a general seasonal guide to important bee flowers

Click here for photos of pollen load colours

Click here for Bee Trees: Horse Chestnut

Click here for Bee Trees: Hawthorn

Click here for Bee Trees: Sycamore

Click here for Bee Trees: Lime

Copyright © Beespoke.info, 2016.  All Rights Reserved.

Click here for more about Irish wasps

Copyright © Beespoke.info, 2016.  All Rights Reserved.

It is when it’s got a great thick woody stem and a big bushy crown with flowers all over it.

Hedera helix 

Depending which book you consult, there is one species of Ivy – Hedera helix and up to six possible subspecies in Ireland and Britain. Two subspecies are present in Ireland – H. helix ssp. helix or Common Ivy and H. helix ssp. hibernica, Atlantic Ivy.  Both are common throughout Britain and Ireland. However, Atlantic Ivy is more commonly found in Ireland, Wales and the western half of Britain while Common Ivy is more common throughout Britain and in the south west of Ireland.

If you want to find out which sort you’ve got – take a close look at the growing shoot-tips with a powerful magnifying glass – if the little hairs (trichomes) are greyish white with star-shaped tips sticking up at angles then that’s H. helix ssp. helix. If they are brownish and lay flat that’s H. helix ssp. hibernica

They also vary in chromosome numbers which means they do not hybridise which makes things easier!

But is it a tree?

What is a Tree?

Consult Chambers Dictionary(1901) and you will find a tree defined as, “a plant having a single trunk, woody, branched and of a large size.”

Or in Collins Pocket Dictionary (1988) a tree is “a large woody perennial plant with one main trunk which develops many branches.”

If you ask Mr.Google he says it’s “a woody perennial plant, typically having a single stem or trunk growing to a considerable height and bearing lateral branches at some distance from the ground.”

All trees go through at least three different growth phases before they can be considered a tree – after all they don’t spring forth from the seed as a large wood perennial with one main trunk and many branches do they?

No they don’t – there are three phases:

• Young – seedling;
• Juvenile – sapling;
• Mature – tree.

Well it’s the same with ivy.

Ivy Growth Phases

Young

Young ivy plants tend to be creeping ground cover until they find something to climb. They are adapted to survive and grow at very low light levels to be found on a forest floor. They do this by growing very slowly.

If it is a deciduous woodland – winter sunshine filtering down through the bare canopy will allow the ivy to continue to grow even in winter.

Juvenile

The juvenile phase involves growth away from the dark forest floor up towards the sunlight. Upwardly mobile shoots put out little sucker feet as they go and attach themselves to their chosen scaffold whatever that may be. As they continue to grow upwards, they put out side shoots or tendrils which strive to encircle the tree – putting out more of those little sucker feet as they go. Where there are several ivy plants growing up different sides of the same tree, between them they weave a twining network like a string vest as they go.

The juvenile phase can last several years during which time several things can happen at the same time:

• The ivy vest matures. It becomes woody and inflexible and tightens up as the individual stems thicken;
• Where stems cross each other, natural grafting occurs and they fuse together making the network even more inflexible;
• The tree, continues to grow adding growth rings and expanding its girth – or trying to;
• The homely old vest turns into a straitjacket.

Just beneath the bark are little tubules called xylem and phoem. These are like our veins and arteries – but instead of blood, they conduct water and the products of photosynthesis around the tree from source to sink.

So while the tree trunk is trying to expand, the ivy cladding is constricting xylem and phloem. The net effect is the ivy starts to strangle the tree.

The slow strangulation can continue for years and during that time the canopy of the tree starts to thin because the tree can no longer support as many leaves. More sunlight comes through and the ivy enters the mature phase.

Mature

The mature phase is when beekeepers and bees start to take an interest in the ivy.

It has a woody stem and with its head out in the light it grows itself a bushy top with many self-supporting branches – a canopy of its own. It now meets the dictionary definition of a tree and with a wealth of lovely sunlight shining right onto its very own canopy – it turns its thoughts to reproduction and comes into flower.

Bingo!

Bring on the bees.

Friend or Foe

Ivy has great value for wildlife but there is debate about whether ivy kills trees or not  and confusion about whether or not it is a parasite.

• Ivy uses trees to climb up but it doesn’t directly parasitise them;
• However,  its roots are cheek by jowl in the same soil as the tree roots so they do compete for water and nutrients;
• They also compete for sunlight. While a tree is in good health – its canopy is dense with layers of healthy green leaves. Little sunlight gets through so the tree is able to keep the ivy in its place;
• However, each winter, deciduous trees lose their leaves and winter sunshine comes through;
• The ivy is evergreen and continues to grow – albeit at a slower rate – all the way through the winter and early spring continuing ever onwards and upwards while the tree sleeps.

Creepy ain’t it?

But the ivy sows the seeds of its own destruction because when it completely colonises the crown of a tree and grows its bushy canopy two things happen.

• The stangulation of the tree means the roots are starting to suffer because they need the products of photosynthesis to survive.
• When the autumn and winter gales come, the bushy evergreen canopy of the ivy acts like the sails of galleon and eventually the two trees – the ivy and its partner tree capsize together.

To Cut or not to Cut?

In a woodland setting this is natural cycling and part of the functioning ecosystem. When a tree comes down  – there is a clearing. Young trees which have been languishing in the dim light of the forest understory put on great spurts of growth as they race up towards the light. Until new trees have regrown, the ivy is banished once again to the forest floor.

However, on trees like ash and hawthorn which grow in hedgerows and have loose open crowns – ivy is a pest. When allowed to rampage away without check – hedgerows are transformed to tottering lines of derelict trees.

Also in parks and gardens it can destroy beautiful specimen trees. In such situations ivy does need to be checked but in the woods it is best to accept it and enjoy it.

For the birds

Ivy provides much needed shelter, roosting and nesting sites.

It also supports many insect species which are food for birds.

Apparently the ivy berries are as calorific as a Mars bar and great for blackbirds although they tend to leave them till everything else has gone.

For the bees

As we know it is a bee plant of some importance – especially here in Ireland. It is a source of late summer – autumn nectar and pollen which the bees use to build up on and boost winter stores.

For those of us who are organised – it can provide a crop of honey when it flowers early.

Click here for more about Ivy Honey

Click here for details on how to prepare for a crop of Ivy honey.

The pollen loads are yellow and in mellow autumn weather they come thudding in like mad.

For the Humans Beeing

Ivy is said to be poisonous if eaten in quantities so don’t do that.

An ivy bedecked stick on the front of a house was once the signal to all and sundry that there was beer for sale.

Perhaps they chose ivy because it is said to cure hangovers.

For the same reason, Bacchus – god of wine – is crowned with a wreath of ivy leaves on his head thus – the twerp:

Or is it because he’s going to fall over soon as well!

Click here for ivy honey cold cure recipe

Click here for Bee Trees – Hawthorn

Click here for Bee Trees – Hazel

Click here for  Bee Trees – Horse Chestnut

Click here for  Bee Trees – Sycamore

Click here for Bee Trees – Willow

Click here for Bee Trees – Lime

Click here for Bee Trees – Poplar

Click here for Melampsora Rust Spores

Sources

Biological Records Centre http://www.brc.ac.uk/

Clapham, A.R., Tutin, T.G. and Warburg, E.F. Excursion Flora of the British Isles. Third Edition. Cambridge University Press. 1995

Fitter. R., Fitter. A. and Blamey, M. The Wildflowers of Britain and Northern Europe. Collins. London. 1985

Keble Martin, W. The New Concise British Flora. Book Club Associates, London. 1978

Metcalfe, D.J. Hedera helix L. Journal of Ecology Volume 93, Issue 3, pages 632–648, June 2005

Online Atlas of the British and Irish Flora

Copyright © Beespoke.info, 2015.  All Rights Reserved.

Poplars are a complex, wind-pollinated, pioneer tree species and they interbreed like mad; as a result they can be difficult to identify. There are many species world wide and several native to Europe. In addition, fast growing hybrid cultivars have been bred and these are much planted for timber. There is also interest in the fast growing varieties for short rotation coppice as a biomass crop.

In Ireland only two Poplars are considered native – although other species have been introduced as ornamental trees or for timber, shelter-belt or screening.

Irish Native Poplars

• European aspen or Populus tremula;
• Black poplar – Populus nigra – although there is some doubt about this one.

The European aspen is a very glamorous autumn tree when the weather is right as this photo below shows. By the way, if you click on any of these photos you’ll get a better view:

And here are some individual aspen leaves:

Note the broadly toothed or wavy leaf margins which distinguish it from the related American species Populus tremuloides or Quaking aspen.

Both of the aspen species have flattened petioles or leaf stems which makes the leaves flutter and clatter in every tiny breeze. Hence the names: tremula and tremuloides.

Non-Native Poplar Species in Ireland

In addition other species of poplar have been planted as ornamentals or as timber trees:

• White poplar or P. alba;
• Western Balsam poplar or P. trichocarpa;
• Many hybrids of P. trichocarpa x black poplar and perhaps P. deltoides x black poplar which can be planted for fast growing timber or as short rotation coppice for biomass cropping.

White poplar or P. alba

The white poplar P. alba is a native of Morocco and the Iberian peninsula and central Europe. It is widely planted throughout Ireland and Britain as an ornamental having attractive leaves with white, felted undersides which flicker brilliantly when stirred by the wind.

Again, it is possible the bees visit the catkins of these early in the year and gather a little pollen but it is not something I’ve ever seen personally.

Western Balsam poplar or P. trichocarpa

In addition is P. trichocarpa or Western Balsam Poplar which has been widely planted as a shelter-belt tree, or for screening, or as a fast growing timber tree. Such as this lovely row below on the river Barrow just below Milford near Carlow. I don’t know why they were planted (she added hastily) but they are in a line and they are lovely. Like all poplars these are thriving close to the river which does flood in the winter. In fact it floods in summer too.

In spring these trees look like the picture below:

A bit plain?

Not at all. At that time of the year, late March, just as the buds are breaking and the new leaves are unfurling – the scent of them is wonderful. It is this smell that gives them their name and any beekeeper getting a whiff of this will immediately recognise it as propolis.  So would the bees who most certainly visit for the propolis and perhaps the catkins too.

These (above) are the late-summer leaves of the Balsam poplar. The slightly serrated leaf-edges distinguish P. trichocarpa from the closely related P. deltoides and hybrids. When the leaves are freshly opened in spring they have a slightly wet look, are sticky to the touch and strongly propolis scented.

In addition to the propolis and the possible catkin-pollen, poplars have a further possible value to the bees Melampsora rust spores.

Melampsora Rust Spores

Poplars are susceptible to a genera of rust fungi called Melampsora. These fungi invade the leaves of poplars causing blisters or pustules which eventually rupture to release the powdery orange spores which no doubt have given rise to the common name of ‘rust’.

Honey bees will gather the spores of Melampsora rusts in times when pollen sources may be scarce. This year I saw my bees bringing in large quantities of bright tangerine orange pollen – or what I thought to be pollen but when I tried to identify it the only thing that was anything like that colour in the pollen guide (and from Mr. Google of course) was Melampsora rust spores. This is what they looked like but the photos don’t do justice to the vivid orange colour of the spores.

An unfortunate consequence for the trees is that the bees are helping to vector the disease.

So that’s three things the bees get from Poplars – a little pollen, propolis and an emergency pollen substitute.

Poplar Timber Uses

Poplars are fast growing so the timber tends to be on the light side. It is used nowadays for paper pulp, joinery, veneers and plywood.

In the past it was used in carts and floorboards and also in a Medieval architectural technique known as cruck building where pairs of massive curved beams were upended and joined to form a roof which was then thatched.

Here’s an interesting one: because the wood is odourless it is considered ‘food safe’ and is much used in France to make those lovely cheese boxes Camembert comes in. It is also used to make fruit boxes. This is why you see so many groves of poplars growing in France – much bedecked with mistletoe.

Still in France – apparently when a landowner has a daughter he plants a grove of poplars. The reason being that by the time she is ready to marry, the poplars will be ready to be felled (fast growing you see!) and the price the farmer gets for the timber is used for the dowry. You learn something new every day – or so they say.

Poplar wood is not much use as firewood because it spits but it can be grown in short rotation coppice and chipped for use in wood burning electricity generators or made into pellets for pellet burning boilers.

For other bee trees:

Click here for Bee Trees – Hawthorn

Click here for Bee Trees – Hazel

Click here for  Bee Trees – Horse Chestnut

Cick here for Bee Trees – Ivy

Click here for  Bee Trees – Sycamore

Click here for Bee Trees – Willow

Click here for Bee Trees – Lime

Click here for Melampsora Rust Spore

References

Edlin,H.L. The Tree Key. Frederick Warne, London. 1978

Hart,C. Practical Forestry. Alex Sutton Publishing, Stroud, Gloucestershire. 1991

Hart,C & Raymond,C. British Trees in Colour. Michael Joseph Ltd., London 1974

Howes,F.N. Plants and Beekeeping. Faber and Faber, London 1945

Isebrands,J.G. & Richardson,J. Poplars and Willows: Trees for Society and the Environment. The Food and Agriculture Organization of the United Nations and CABI . http://www.fao.org/3/a-i2670e.pdf

Kirk,W.D.J, A Colour Guide to the Pollen Loads of the Honey Bee. IBRA 1994

Phillips,R. Trees in Britain, Europe and North America. Pan Books. London. 1978

Strouts,R.G & Winter,T.G. Diagnosis of Ill Health in Trees. Forestry Commission. 1994

Copyright © Beespoke.info, 2015. All Rights Reserved.

An alternative explanation for its arrival in this side of the world is the cotton industry. Balsam seeds came in with raw cotton bolls and during the cotton milling process they escaped into the rivers. The cotton mills being powered by water were of course situated close to fast moving water. I like this idea because it fits neatly with childhood memories of holidays in Lancashire 50 years ago where Himalayan balsam was a common occupant of stream banks and ditches. Like the ditch near the sweet shop where we used to buy sherbert in paper cones.

Ecological Disaster Area

Himalayan balsam has become unpopular because it spreads very quickly along watercourses and pushes out the native perennial vegetation.

Ok says you – may the best man win, it is very pretty and the bees love it. Not so fast says I and look what happens when winter comes:

• Himalayan balsam dies because it’s an annual;
• River banks are left bare because not much is going to grow in winter;
• Winter water levels and faster flowing water erode the naked river banks;
• Hey presto – flooding.

Description

The fancy name is Impatiens glandulilfera the same family as Bizzy Lizzies: aka Impatiens walleriana. ‘Impatiens‘ because the ripe seed pods burst – impatiently – in your hand, firing seeds into the distance.  The ‘glandulifera’ bit relates to its creepy mucus-secreting glands which are thought to be redundant artefacts inherited from carnivorous ancestor plants. The unpleasant rank smell is thought to come from the mucus. That smell takes me right back to the sweet shop and the sherbert.

Actually when you look at the pink or white flowers there’s a bit of the Pitcher plant about them with that frilly-lipped, gaping mouth and bulbous back end.

The plant is tall and stately – often topping 6ft in height – taller than many policemen nowadays. It can possibly reach as high as 10ft.

You’ll recognise this chap of course – this is the actor Jack Warner as PC George Dixon in the black and white 1950 film ‘The Blue Lamp’. You’ll see from his old style police helmet exactly how the Himalayan balsam got its common name. The flowers are approximately the same shape but as if worked on by a gay milliner.

After his success in ‘The Blue Lamp’ (1950) with Dirk Bogarde – PC Dixon escaped the confines of the old black and white movie and went global (like Himalayan balsam) as ‘Dixon of Dock Green’ occupying TV screens across the nation from 1955-76 by which time he was in his eighties and available in colour.

But I digress.

As a bee plant

It is a very popular and reliable plant for the bees who will travel some distance for the nectar. Flowering as it does in August it fills the gap between the end of the summer main crop and the autumnal ivy flow helping the bees going into winter.

Popular too with beekeepers who may take a late summer crop from it.

You will know if your bees have been on the balsam as they will have a distinctive white smudge of pollen on the thorax like this:

Copyright © Beespoke.info, 2015.  All Rights Reserved.

One of my apiary sites is in a nature reserve on a small raised bog in Kildare. The clover and blackberry are in full bloom all around the fringes there so I expected to find the bees with brown or grey pollen loads. However, I was surprised to find them bringing in a lot of vivid orange pollen and no, that’s not propolis. Of course I’d come out without my camera so had to make do with my phone and these pictures don’t do the colour justice. Click photos to enlarge.

When I consult the relevant pages of  IBRA’s:  ‘Colour Guide to the Pollen Loads of the Honey Bee’ by William Kirk, the only one I can find which is both close in colour and available in quantity at that site, is Poplar leaf rust fungus aka Melampspora larci-populina!

If you google that, you’ll find some images of the rust on its host species  and you can imagine it packed into honey bee corbiculae.

It seems that the bees will indeed gather rust spores in times when pollen is in short supply. As the bees visit poplars to gather propolis you’d have to wonder if they help in the spread of this fungus?

Click here for more pollen load photos

Copyright © Beespoke.info, 2015.  All Rights Reserved.

Or you might wonder – ‘IS there a flow at all?’ Because often there isn’t and you can never tell in advance if it will or if it won’t. Heather honey is the most bewitching and frustrating of all honeys; if you can get a crop of sections or cut comb honey it’s close to heaven and so costly and disappointing when it fails.

But there’s more to it than the weather. It’s the ecology – Stupid!

Distribution

Calluna vulgaris or Ling heather is widespread at all altitudes across Northern Europe from Spain to Scandinavia and from the Azores to the Urals but tends to dominate where the environment is harsh and/or nutrient stressed. As we all know, it tolerates extreme cold without damage but it is intolerant of shade.

Soil

Calluna is seldom found in fertile lowland situations because it is a ‘calcifuge’ ie it can’t bear limey or base soils but likes instead, an acid soil. This tends to make it a plant of stressed environments, either mountain or bog where excessive rain and cold create acid soils which are also usually low in available nitrogen.

It can get a foothold in moderately receptive soil environments. Once established, the cast-off leaves decay to a dark brown acidic humus. In this way Calluna is able to adapt certain soil environments to suit its own requirements.

Moisture

While Calluna is almost always found in areas of high rainfall – it is actually intolerant of waterlogging and grows best where there is moderate drainage. In super-saturated areas Calluna tends to give way to Ericaceous heathers ie Erica tetralix or E. caerulea – also Molinea caerulea or Purple Moor Grass.  Where Calluna is found growing in bogs, the roots tend to be restricted to the top few inches of peat and above the upper extent of the summer water table. If this is still too wet – it will pull up its skirts and occupy the hummocks.

Growth Habit

When it finds conditions it likes – C. vulgaris is a long lived, woody dwarf shrub – often reaching 30 and even 35 years old. The life cycle is divided into four phases:

• Pioneer – 3-6 years – flowering after the 1st year;
• Building – Up to 15 or 20 years. Densely branched shrub with maximum canopy cover and nothing growing beneath. Flowering freely;
• Mature – Over 20 years. Plants become leggy – up to 1.2 metres – with mosses and lichens beginning to occupy the open area at the centre of the plant;
• Degenerate – Over 25 years. Central branches die out leaving a gap which may be colonised by other species perhaps upland trees such as Rowan or Scots Pine before young Calluna plants can establish.

For the beekeeper, the Building and Mature phases are most useful to the beekeeper as they can give rise to vast areas of carpet-form heather which is when flowering is most profuse.

Careful burning of heather at intervals in concert with managed grazing can remove stands of degenerate heather and create instead a shifting mosaic of different aged stands of heather which are of great benefit to wildlife – especially Red Grouse (Lagopus lagopus), many species of bees and other insects. Beneficial to Hill farmers also.

Burning correctly is a skill. Ideally the fire should only kill over-mature specimens leaving younger plants to regenerate from the base and creating space to allow seeds to germinate. A slow moving fire over dry peat can get too hot, killing all heather plants and destroying the seeds present in the seed bank. In such cases regeneration is slow, if at all, and other species may move in instead. And there may be soil erosion.

Grazing

Calluna benefits from moderate browsing which can promote the aforementioned dense, single-species, topiaried carpet.

Sheep and Deer are browsers rather than grazers such as cattle: they pick and choose – mostly young shoots which is like light pruning and beneficial in its effects. However, overstocking of  sheep/deer forces them to browse more deeply, and damagingly, into the woody heart of the plant. It also reduces the ability of heather to regenerate; young plants are unable to establish or are grazed to extinction leading to thinning stands of gangly, senescent heather. Excessive trampling creates bare patches leading to soil erosion or invasion of other less valuable species.

Cattle are disastrous for heather – they graze indiscriminately and their great heavy feet cause severe damage to soft peaty soils leading inevitable to soil erosion.

Heather also provides habitat for the Red Grouse (Lagopus lagopus) which relies on heather for 90% of it’s adult diet. It also requires heather of varying ages  for shelter and cover and areas in which to nest and to rear young. The young birds are reared on insects foraged in the heather – the only carnivorous phase in the bird’s life. As such it is completely dependent on heather for its life-cycle.

I never heard of overgrazing by grouse – instead this bird can be regarded as the ‘canary’ when recognising when conservation is necessary. In other words – if it is absent or dwindling from heathery uplands something is wrong. Click here for the Irish Red Grouse Association.

Heather Beetle is a wild creature whose boom-and-bust life cycle can lead to overgrazing by the larvae and even death of great swathes of heather. Sometimes the whole system is replaced by other less desirable vegetation communities such as Molinia caerulea  aka Purple Moor Grass with or without assorted sedges and moss. This creature, the heather beetle is also known as Lochmaea suturalis. Here it is:

In a ‘normal’ year, heather beetle harmlessly carries out its life cycle eating heather leaves and hibernating in the soil. However in some years the population rockets and the heather suffers a beetle-grazing epidemic to the extent that extensive areas are wiped out.

Here’s a picture of severe heather beetle damage in a lowland raised bog, Narraghmore, Co.Kildare:

Pollination

The flowers of Calluna are able to both self and cross pollinate but an outside agent either the wind or an insect is required in both cases. In experiments where flowers are enclosed and outside agents excluded, pollination does not occur.

If you look closely at the flowers of C. vulgaris you will see that the arrangement of pollination paraphernalia lends itself to a generalist approach enabling both insect and wind transfer of pollen.

Either way, once a flower is pollinated by the wind or another insect rather than one of your honey bees, the secretion of nectar dries up!

Wind Pollination The pollen-bearing anthers are safely enclosed within the heather flower. When weather is damp and wet, the pollen remains clumped on the anthers and is not washed away by the rain.  When weather is dry and windy, however, it is liberally shaken out and blown hither and yon. The stigmas meanwhile are out in the elements where they can obviously take advantage of passing clouds of pollen. So if there is a long period of dry windy weather and the flowers are quickly wind pollinated the likelihood of a strong nectar flow is reduced.

Here’s a picture of my dog Bunty in the heather. She used to love a trip to the hills but the poor girl was the victim of a pollen allergy and the free release of heather pollen on a sunny day would set up such an itch she would spend most of her time rolling around and scratching till she bled.

Insect Pollination  We are all familiar with the buzz of activity in the flowering heather what with bumble bees, honey bees, butterflies and others. Flowers are visited by about 35 species of insects.

Nectar to attract insects is secreted from nectaries inside and at the base of the flower below the anthers.  As such, visiting insects inevitably transfer pollen from their bodies onto the stigma and pick up pollen from the anthers as the reach down for the nectar.

Bumble bees and honey bees are the most efficient pollinators as they carry the most pollen and they get up very early in the morning!

Thrip pollination The architecture of heather flowers does not allow for rain pollination. However where Calluna lives it can rain for days or even weeks on end.  No surprise then, that heather does have a trick up its sleeve for those wet years when neither wind nor flying insects can do the job.

There is a tiny creature – a thrip – called Taeniothrips ericae – which is found on both Calluna and Ericaceous heathers. It spends almost its entire life cycle within the flowers, romping about between the anthers picking up pollen and eating nectar.  There are about 4-6 thrips per flower but male thrips are rare. As a consequence females leave home on sexual maturity and roam from flower to flower looking for a mate. The picture below from Hagerup (1950) shows a female thrip using the stigma of a flower as a launch pad (Figure 2.). No doubt she lands on many of these during her wanderings and inevitably pollination must occur. Later work in Norway by Haslerud (1974)  concluded that pollination by thrips was only significant in very wet climates. Click picture for a close up.

By the way, pollination aside, these insects have the same boom and bust life cycles as the heather beetle and Irish developers. In boom years each flower may be full of baby thriplets eating all that heather nectar before our bees can get there. And you know yourself how the honey bee hates competition – they’ll just go for the ivy instead!

In Essex I remember plagues of tiny black corn thrips or ‘Thunderbugs’;  some years the air would be full of them. They’re probably extinct now.

A Hardy Plant?

In the absence of over-grazing by mammals, birds or insects – Calluna fares surprisingly well in hostile environments on acid/nutrient poor soils and in cold, wet, upland areas with strong winds etc. It grows quickly into a large, long lived, vigorous plant which puts out a profusion of flowers year on year.

How does it do it?

Read on…

Mycorrhizal Symbiosis

To cope with the stresses of the very extreme environments of mountain and bog, Calluna has evolved a  symbiotic relationship, with an assortment of soil fungi including Rhizocyphus ericae and Phialocephala fortinii complex. Fungi involved in these symbioses are termed Mycorrhizae or ‘fungus roots’.

Don’t go away – this is simpler and far more interesting than you can imagine!

Here is the simplified basis for Calluna’s mycorrhizal symbiosis:

• Calluna is nitrogen-limited because there is so little available in the stressed environments it inhabits but it does have an unlimited supply of carbon which it captures from the air via photosynthesis.
• Fungi, on the other hand, are enzymatic powerhouses – well able to break down acidic litter and suck up nitrogen in conditions which thwart most plants. As a result, soil fungi have an abundance of nitrogen but they are carbon-limited.

The roots of the heather link up with microscopic fungal hyphae thus plugging themselves into a fungal network of mycellium which ramifies outwards through the soil breaking down litter and supplying nitrogen to the plant which in return supplies carbon products to the fungus.

There’s more – these fungi are termed endomycorrhyzas which means they actually penetrate the roots and grow inside the plant as well – a hand in glove relationship! Fungal hyphae can be found throughout the plant even as far as the ovules with their ripening seeds. Sounds a bit like The Borg (1992,1996) don’t it? Researchers believe that in this way, plants are inoculated with their mycorrhyzal partners when they are seeds – how clever is that!

Conservation

A survey of potential Red Grouse habitat in Ireland in 2008 revealed 22% of the total grouse habitat to be severely damaged by overgrazing, 30% moderately damaged while only 34% remains undamaged. For Red Grouse Habitat read Calluna vulgaris.

It should be of concern to beekeepers as well as sheep farmers that over 50% of total heather is damaged.

Sources

Crushell,P. & O’Callaghan, R.J. (2008) A Survey of Red Grouse (Lagopus lagopus) Habitat in Ireland 2007 – 2008: an assessment of habitat condition and land-use impacts. Report for BirdWatch Ireland & The National Parks and Wildlife Service, Department of the Environment, Heritage and Local Government, Ireland.

Gimmingham,C.H. (1960) Biological Flora of the British Isles: Calluna vulgaris Journal of Ecology

Hagerup, O. (1950). Thrips Pollination in Calluna. K. Danske vidensk. Selsk., Biol. Medd., 18 1-16

Hazard.C., Gosling.P., Mitchell.D.T., Doohan.F.M. & Bending.G.D. (2013) Diversity of fungi associated with hair roots of Ericaceous plants is affected by land use. Article first published online: 28 NOV 2013. DOI: 10.1111/1574-6941.12247. © 2013 Federation of European Microbiological Societies

Haslerud, H.D. (1974) Pollination of some Ericaceae in Norway.
Nord. J. Bot. 21: 211–216.

Mahy, G., De Sloover, J., & Jacquemart,A. (1998) The generalist pollination system and reproductive success of Calluna vulgaris
in the Upper Ardenne. Can. J. Bot. Vol. 76 1843-51

Mohamed, B.F. & Gimmingham,C.H. (1970) The Morphology of Vegetative Regeneration of Calluna vulgaris. New Phytologist. 69, 743-750

Rayner,M.C. (1925) The Nutrition of Mycorrhiza Plants : Calluna vulgaris. Journal of Experimental Biology

Star Trek: The Next Generation: I Borg  Season 5, Episode 23 (1992)

Star Trek: First Contact (1996)

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