Invasive Weeds

Spiraea Escaping from People's Gardens

2012-02-04T04:12:00.001-08:00

Invasive Weeds from Alaska

There are many types of Spiraea, from much of the Northern Hemisphere. There are shrubby forms as well as some that are Herbaceous, such as our own native Meadow Sweet, although that has since been re-classified as Filipendula.

Many well behaved garden varieties exist, which never cause any problems, but this one is a real nuisance. On the picture above; clearly irresponsible people have dug it up from their gardens and just lobbed it onto the land behind, where it has began to try and engulf the whole site.

Spiraea douglasii is a highly invasive species of this genus. Spreading aggressively from underground roots. It is native to western North America from Alaska, across southwestern Canada and the Pacific Northwest, but not here!

This is Not Wild Garlic!

2012-01-28T08:48:00.001-08:00

A commonly Made Mistake

The above plant is not Wild Garlic. The one to the right is. It is a very commonly mistaken for it, but there are a number of obvious differences:

It has a three sided flowering stem, where as Garlic has a rounded stem.
It flowers earlier than Wild Garlic and can continues to throw off flowers at obscure times of the year. The Garlic, on the other hand has all its flowers at the same time in April.
It has thin leaves, instead of the flat rounded leaves of the Wild Garlic.

It is not anything like as nice to eat as the Garlic and in large quantities; can cause mild effects of poisoning.

The plant was brought over, as usual; to grow in peoples gardens, where it quickly takes over and becomes a weed in everyone elses garden.The Three Cornered Leek or Stinking Onion Allium Triquetrum is an invasive weed from Southern Europe, where it grows along the coast of the Mediterranean. It is also said to grow along the Pacific coasts of Oregon and California.

I think Torquay in South Devon provides a very good example of how bad this plant can get. In Cornwall too, especially in gardens and woods around seaside towns, usually if it is present; its in every garden, but sometimes also in hedges and woodland.

I find that, even in areas, where this plant is very common and a real nuisance; most people think it's Wild Garlic, but it most defiantly is not! I hope they haven't tried eating it!

Hollies are Native Trees, but Under the right conditions, they can become a Pest!

2012-01-21T12:05:00.001-08:00

Friend or Foe?
Holly is one of our most well known and documented native trees. It has evolved alongside our other native vegetation and wildlife, and it usually forms a natural balance with in our woodlands, heaths and hedgerows.

Normally there is just the right amount of it and it is a fairly common. A well behaved little tree, giving shelter in the winter and berries for the Birds.

Under certain condition, however; Holly can quickly become a rampant nuisance, spreading mostly from seed, often engulfing the entire under-canopy, in a similar fashion to many invasive foreign weeds, such as Rhododendron, Bay or Cherry Laurel.

There seems no clear indication of what exactly triggers the Holly to behave in this way, but my observations, over the past few years; have lead me to conclude with two main theory's.

Hollies Take over in some wild areas, But not in others

What ever could be causing this strange phenomenon?
I will go more into my own conclusions in a bit, but firstly, I would like to show some examples of a few wild woodland areas on Dartmoor national park, where Hollies have really made problems and become a dreadful invasive weed, in their own right.

The caption on the right, shows just how quickly Hollies seed themselves, when they become troublesome. From other pictures on this post; you can see how they rapidly take over.

These photos were taken on three sites. Two of the sites were completely taken over with Holly, but in the third; Holly was common, but behaving normally.

Other observations have shown me that often coastal areas are particularly at risk from such natural unrest.

Theory's

I have, as I already mentioned got two main theory's for this unnatural Holly growth, but I shall mention a third theory here as well:

Young Woods - One clear observation as shown that Hollies don't seem to be anything like as invasive in a fully mature woodland and younger half grown trees perhaps do not block the light from the under canopy quite as much as so make conditions ideal for them to take over, which would perhaps mean that when such wood do reach maturity, perhaps the problem would solve its self.
Climate Change - Perhaps the change of our climate over recent decades has created conditions, which favour our Hollies and they have had a population explosion as a direct result of this.
Garden Hybrids - Its possible that our wild Hollies could have become hybridises with many new and exotic garden varieties and foreign species and have developed into a disease resistant super-weed.

What ever is causing this problem, it really dose need some further investigations. I aim to keep an eye on the behaviour of these plants and hope that the problem subsides and this plant goes back to its normal balanced pattern of growth.

South African Invaders

2012-01-18T01:29:00.001-08:00

Sickly Orange, as far as the eye can see.

Monbretia/Crocosmia might look pretty in the late Summer, but it is not our friend!

The late Summer often poses a problem to gardeners, because most of our garden and wild flowers have finished and gardens can look very bare. Then along came Monbritia, which is now known as Crocosmia.

This Orange invader from South Africa has evolved to be so tough, to survive the harsh conditions in its native homeland.

they can survive in just about any conditions. Being just as much of a nuisance in damp as in dry, although I haven't yet seen it growing in boggy ground. It loves direct sunlight, but thrives just as well underneath evergreen woods and/or shrubs. It is shown here spreading unhindered and flowering underneath a conifer plantation on the top of Dartmoor.

I would say that the sea cliffs at Boscastle, Cornwall would be the worsted effected place, I have ever seen, but this pest is a wide spread problem and extremely difficult to eradicate as it has dormant corms, under the ground.

The corms are like mini Gladioli corms, but are stacked one on top of the other, all lie dormant, except the one at the top, which has the leaves sprouting from it. Making them very difficult to eradicate from either poisoning or digging them up; there is always another bit that's down there that you have missed. And as far a poisoning goes; any Systemic poison is only going to work, if it can feed poison from the leaves into the corms, but if most of the corms are dormant; the poison is effectively useless.

I have never known Monbretia to spread from seed it's self in this country, it usually relies on ignorant nimby gardeners, lobbing it in hedges. It spreads its self, with long rhizomes, which arm out in all directions and they always form a dense spreading clump of pestilence.

Crocosmia, Newer Bigger Monbretia

Newer Bigger Arrivals from Garden centres and a discrete name change

I was taught, that this plant was called Monbretia, was I was a child. Indeed all the older customers I have ever worked for as a gardener; have called it Monbretia. But then suddenly it was re-packaged and renamed and marketed as 'Crocosmia', a newer, bigger, faster spreading selection of varieties and species of this terrible plant, arriving in garden centres across the country and probably; the world.

As you can see, from this picture to the side here; this Crocosmia, is far bigger than its smaller relative. It spreads just as fast and has the same arrangement with its corms, but its corms are bigger and deeper.

This unwelcome clump as spread into my garden from some neighbours, who don't even know what it is. When I informed them about it, they basically said it looks pretty and nothing else will grow for them. Where have I heard that one before?
Surely having a garden, just like having a farm; is a responsibility?

Fly-tipping

This is the most common way that this group of foreign invasive weeds enters many wild environments.

Ignorant yobs, who can't deal with or confine the problem to their own garden, think they have the right to ruin our precious Eco-system, just so that they don't have a problem.

below are two photos of some fly-tipped Monbretia/Crocosmia, which I found in a woodland, only a few days ago.

Rododendrons Invade Dorset Countryside

2012-01-17T12:06:00.001-08:00

NO NATURAL PREDATORS!

Nothing eats it! No diseases attack it! It is poisonous, in fact; very poisonous and it spreads at a phenomenal rate, both vegetativly, as it spreads procumbently along the ground, but mostly from its million of tiny seed, which are also very poisonous.

Back home in its native Himalayas, the Rhododendron has a natural balance with the other wildlife in its area, which it has evolved in unison with. It has diseases which attack and sometimes kill it, it has bugs and beasties which munch its leaves, but here it has none of that to contend with, and just look at the devastation caused to the under canopy and forest floor, when nothing else grows, besides Rhododendron.

Can't See the Woods for the Rhododendrons

If this part of Dorset wasn't so flat, or if I felt energised enough to climb up a tree; I could have shown you a wood-scape, in which the forest floor is completely Rhododendron. But I think the pictures on this post, give you a pretty good idea of how bad the problem is. Even under a dense canopy of conifers; these things rampage monstrously through our precious Eco-system. A solid tangle of twisted branches, masked by a 20 foot/3 metre blanket of toxic, useless dark green uninviting leaves.

Left to their own devices even our large trees would mostly die out, since seedling trees cannot penetrate this dense under canopy and new trees from seed cant grow, because there isn't enough light down on the forest floor.

Rhododendrons on the other hand seem to thrive in an conditions in the UK, but greatly prefer the shade of large deciduous trees.

Invasive Species of Rhododendron

There are three main invasive species in the UK, out of all the many hundreds of species and varieties, which have been brought over from abroad or hybridised.

The species featured here is Rhododendron Ponticum. There is no doubting, that this one is the worsted invasive species of Rhododendron in the UK by far.

Pines of Parkstone

2012-01-11T17:13:00.001-08:00

BH13
BH13 is defiantly an unlucky 13 for this exclusive Parkstone, Poole Postal code area. This place is set to burn.

Parkstone is part of a sprawling sea side conurbation, formed by three major towns, being very close together, along the south coast of the UK; and having become just one big urban lump, but with each town insisting on its own independent status, which makes getting here just that little bit more tricky, since you can not refer to the Lump by just one name.

BH13 is classed as part of Poole, which is the poshest of the three main towns, in the conurbation & this particular bit of Parkstone, is its poshest bit.

Like everywhere else here; BH13 is completely over run with Pines and other highly flammable evergreen trees. Looking round this area; people have little else in their massive gardens, other than tall twisting Pine Trees & pretty much every garden has lots of them. Right up to the eves, windows and doors of their houses.

Pretty much everything here is evergreen and most of it Pine.

The Stone or Maritime Pine Pinus Maritima is the one that grows abundantly on the Mediterranean coast, like in the South of France. Its the one that they get the Pine nuts from.

Pinus Maritma along with many other species of Pine needs fire as part of it's reproductive cycle; when the woods burns, it becomes hot enough for the Pine cones to open and to drop their seeds to enable the next quick growing generation to take root.

fire also eliminates much of the competition and might explain why there are barely any of our native deciduous trees or wild flowers here.

Basically its in the Pine trees best interests to burn, and the older they get; the more flammable they become. from the dry, dead slow rotting twigs and branches to the ignitable dry Pine-needle leaf litter, which covers the forest floor.
These trees have evolved to encourage fire, which not just burns down all the other trees, but will scour and burn the topsoil as well.

People here have many tales to tell about heath fires & it doesn't take much driving about here, before you start noticing the odd scorched bit.

A huge, uncontrollable fire here is inevitable, just like in California, The Mediterranean and in Australia. I bet when it comes it takes quite a few of these 3 million pound houses with it.

Parkstone Golf Course
My late Grandad used to live here and back onto this golf course. He has been gone for quite some time now, I used to come here, when I was very little. My Grandad was born in 1900, so if he was still alive; he would be coming up to his 112th birthday.

As you can see, from these pictures; Parkstone golf course, like everywhere else here is completely Pine!
How can and area become so over run so quickly?

People here say that its because of the strange yellowish sandy soil here and the mild climate. But I am not convinced that this problem is safely contained here.

Walking around Poole is like being in a different part of the world. It is not like the rest of the country. Everywhere else is light green, here is dark green.

The contagion spreads right down to the bottoms of the sea cliffs and way inland, to many outlying areas.

To me the problem seems to be spreading and in tree terms; its spreading fast.

With every year that nothing is done about it; the pine army spreads and begins to take over and brings fire to new areas and could threaten to take over a great deal more land than it currently occupies today. maybe even the whole of the South. Maybe even the whole country.

Holm Oaks Take Over allong the South Coast

2012-01-11T12:13:00.001-08:00

The Mediterranean Look
Evergreen woods reaching down to white beaches. You might be easily mistaken, for thinking this is a view from the foothills above Dubrovnik, in Croatia, or perhaps somewhere along the coast of either Spain or Portugal; but no! This is Poole in Dorset and apart from Holly; these woods have none of our native trees at all! What's going on here?

Every park, every woods or heath; the same bland mixture of non-native evergreens.

I don't think I have ever seen a part of the UK so besieged with foreign weeds. It is so bad that Beech and Hazel actually seem to have become extinct in this part of the South coast. How could they let it get this bad?

Control of Holm Oaks
As you can see, from these England supporting tree stumps; the local authorities here have been making some puny efforts to control this problem.

If they have been doing it right; they should have cut them down in the growing season and then roughed up the stumps a bit, to give the maximum wounded surface area and then painted on some tree poison.

They have certainly painted them, but as far as poisoning them goes; they really do seem to have done a very poor job here and not made any effort at all anywhere else.

As you can see here, from this left caption; the stumps quickly regrow and in only a few years, the canopy will reform and the sunlight will again be swamped out.

There are seemingly no native trees left here to recolonise this area. Removing these evergreens would leave Poole with no trees.

Perhaps doing one bit at a time and replanting each bit with native trees.

Whatever way this problem is tackled; the authorities have a big job to do here & a job which gets bigger and bigger the longer they sit there and do nothing.

Below; the view from the beach, shows how wide spread the problem is:

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Invasive Evergreens in Suburban Coastal Dorset

2012-01-08T12:51:00.001-08:00

Warming Climate and Irresponsible gardeners
A combination of our climate becoming less harsh, especially in the winter & irresponsible gardeners, growing many varieties of invasive weeds in their gardens; has produced an explosion of evergreen trees and shrubs, mostly around our coastal towns & cities.

Some of these evergreens are native, others are not. But whatever the origin; these trees are running a muck and it would be interesting to find out for sure; why they are doing this.

Pine Trees
Some parts of the Uk's south coast are starting to look like the South of France, with all these pine trees. There are a few different species, which seem to be causing the nuisance, but its unclear where they came from in the first place, they certainly do well here. In some woods, nearly all the tall trees are Pine trees, I wouldn't like to be here in a drought; these things go up like match wood.

The more urban the area; the more pine trees & other evergreens are to be found. This would strongly suggest that they have escaped from gardens, but it is possible also that some may have escaped from commercial plantations as well.

There are allot in gardens and parks, though I suspect most, if not all are self seeded.

Holly
Not a foreign plant, never the less; spreading in the under canopy, like an unstoppable tidal wave.

Why is this otherwise fairly well behaved tree, which should be (and usually is) naturally balanced and attuned to the Eco-system/habitat here; be behaving like this?

Vast areas of heath and woods alike are covered in the stuff. I haven't seen one Hazel!

Bays and Laurels
Worse than the Hollies, this group of similar and related plants spread uncontrollably, throughout woods, heaths and unkempt gardens alike.

Some, like the Cherry-Laural (left) will even devastate areas well inland and will even damage woodland at high altitude. Spreading with the virility of a Rhododendron, over the forest floor and extinguishing the light from all but the very tall trees.

Bay trees are often thought of as a difficult to grow garden herb, which dies if there is a harsh winter and regrows from the base, if you're lucky. But here, on the south coast, they don't have very low winter temperatures and just go on growing. in some areas, they dominate the under canopy completely.

There are many other relatives of these plants; like the Bird Cherry and the Portuguese Laurel, some of these too are joining the invading army of Evergreens; deleting our native plants, from right under our noses.

Holm and Spanish Oaks
The Evergreen Oaks.
These trees thrive on the South coast. Quickly spreading into new areas and waisting no time in grabbing large percentages of the canopy space from our native trees.

Naturally they grows in the South of the temperate zone in Southern Europe, mainly Spain and Portugal. They are close relatives of the Cork Oak, which is famously produced almost exclusively in Portugal.

But why are they here? Blasted gardeners again , I expect. But where ever they came from, one thing is clear; We have a real problem here.

Cotoneaster
Defiantly from people's gardens, this one! A real nuisance!
There are allot of different species of it. Some evergreen, some deciduous and some in between. Many are highly invasive, mainly in Heaths and Hedgerows.

They are spread by Birds and the berries look pretty all through the winter, so people have them in their gardens to give screening, winter colour and to attract the birds. I wonder how many of them are even aware of the damage they are responsible for.

Budlejia
The Butterfly Bush

This one is a menace, mainly around urban areas, be they coastal or otherwise, although it is far more widespread at lower altitudes, spreading quickly and colonising waste areas. Growing more quickly than our native species can and so; swamping them out.

Gardeners tolerate it's appearance in their garden, because it flowers and gets covered in Butterflies, which has an obvious appeal, but many other flowering plants are enjoyed by Butterflies, just as much. So there is no excuse!

Budlejia needs few resources. It grows on sheer rock or quarry faces, as well as from between the mortars of buildings, as seen here; quite a few can be seen, sprouting from brickwork, in this railway arch,to the right.

Today's Coastal Woodland

To me; the above picture looks like 'a scene of destruction'! Compare this with an average picture of pristine English woodland and it is a totally different kind of environment. It is far more like the Evergreen woodland, usually found much further south on the Mediterranean, although many of these invasive weeds come from different corners of the world, including the Himalayas.

Very little space seems uncrowded with dark, engulfing Evergreen. Apart from the odd Oak and the masses of Holly; it essentially is no longer native woodland, scarcely even remotely native.

Plants and animals evolve together and build up Eco-systems. If these coastal areas are a blue print, for what is to come, then we could be looking at many localised mass-extinctions, right up the food chain, as these foreign weeds keep on coming relentlessly and unchecked.

Indian Balsam

2011-10-01T05:03:00.000-07:00

Impatiens Grandiflora

Another Himalayan pest

Considered the worsted invasive weed of all

Brought here by 19th Century gardeners, from various parts of the Himalayan mountains, like so many others of our 'die-hard' invasive weeds. This one doesn't have deep roots, in fact it is a half hard annual, like it's cousins the Busy Lizzie's, also Impatiens and commonly used as summer bedding plants. Indian Balsam is fortunately only confined to growing along water courses and on damp ground, however it produces so many seeds, that it soon takes these areas over completely and leaves little or no room at all for the wide variety of native swamp plants, which include a wide variety of Orchids; among many other types of plants, pushed to the edge of extinction, by this monster.

Indian Balsam often gets to 2 metres in height and it grows just as well under trees as it dose in full sun.

The Environment Agency, here in the UK, consider this plant to be our biggest problem, with regard to invasive weeds. Simply because of it's ability to spread by seeds and it's ability to re -root, when pulled up, if left in a damp location. Personally I think it is neck and neck with Rhododendron, but the infamous Japanese Knotweed is considered less of a threat, despite its deep rhizomes, simply because it cannot seed it's self here.

Exploding Seed Pods

As you can see, from the above picture; there are many big fat seed pods. The riper they get, the more primed they are to explode. Just a slight touch of a ripe pod, will cause it to burst open quite violently, casting it's seeds many metres, in all directions. They occupy most river valleys in the UK, from source to mouth, even up on Dartmoor, they swarm and multiply in the swamps like locusts and they seem to be an unstoppable force, destined to destroy much of our native fauna, and cause a huge reduction in biodiversity, which in turn affects the whole food chain.

Just look at this picture below; a whole swamp, completely taken over by it. I don't really understand the point in having a nature conservation area, as this is supposed to be; if they just allow plants like this to destroy most of the native plant species.

Control

Any control of this weed, needs to be organised and thorough. There is little point in removing a bit from one area; because it will simply spread back there again. It needs to be done one valley at a time, from source to mouth and up every tributary and in every garden, where it resides.

Pulling it up and then taking all the tons of material some where dry, but that would cost a fortune, even in just a small area like here in the Exe Valley; this plant is everywhere.

I have removed bits up on Dartmoor, but it's an up hill struggle, really; I need lots more help. But great in roads have been made towards the eradication of Rhododendron and Japanese Knotweed, the Environment Agency is aware of the problem, so hopefully it will just be a matter of time before this menace of our waterways is gone forever.

Cotoneaster

2011-10-01T01:37:00.000-07:00

My Granny used to boast, that I told some person in the park, the name of this plant, when I was about 2 or 3 years old. It's true, I remember it. But what I didn't know then; was that it is a nasty invasive weed, from India. We gave them Gorse, which causes them allot of problems. Gorse in India, is a real nuisance. They gave us Cotoneaster.

You might think, 'how dose a tropical plant grow here?' you might correctly point out that India has day time temperatures of about 46-degrees C. Well, allot of India is mountainous and allot has snow in the winter, such as the Himalayas, where many if not most of our particularly nasty invasive weeds come from. I suppose that after they have survived the tough conditions there, here is very easy for them and then they take over.

When I went to India; the temperature at 4am was 32-degrees C. I always take a thermometer when I go to the tropics.

There are many different species and variants of this plant + quite a bit of hybridisation. Wretched people plant it in their wretched gardens. The birds eat the berries and that is how it spreads far and wide, with hedges and heathland, being the worse affected areas. It tends to take over whole swathes of land, once it gets a hold, but requires quite allot of sun and dies off once the main sequence trees grow through the scrub, to dominate the canopy.

The plant dose have obvious appeal; it is very easy to grow, will survive just about anything and has berries for much of the latter part of the year. Most species are evergreen, so it also provides good screening. But our wildlife, with the exception of birds don't like it, it displaces our own native plants and it makes us just one step closer to an homogenised world, in which just the same few very aggressive and dominating species engulf the whole world.