Wednesday, November 30, 2011

A Tree-spotter's Guide to Conifer Cones: 1

We are in the Christmas tree season - a Baltic state and German tradition introduced into Britain by George III's queen and popularised by Queen Victoria's consort Prince Albert and  by Charles Dickens - so what better time to take a look at conifer cones?
Botanically, conifer cones are spiral whorls of scales arranged on a common axis, with each scale bearing a pair of ovules that develop into winged seeds after pollination and maturation, when the cone becomes woody, opens and releases them.

This is Douglas fir Pseudotsuga menziesii, easily recognisable by the papery bracts, like three-pronged tongues, above each scale. Its common name commemorates David Douglas, the Scottish plant collector who in 1826 introduced this tree into cultivation. Douglas led a colourful life before coming to an unfortunate end when he was gored to death by a bull in Hawaii, at the tragically young age of 35.. The Latin specific name commemorates Archibald Menzies, another great Scottish plant collector who discovered the tree in 1792. Douglas fir is a giant tree in its native west coast of North America, where some trees may have been even taller than giant redwoods, reaching almost 400ft., before the finest trees were felled for their exceptionally fine timber. Trees introduced into Britain grew very rapidly, with some now exceeding 200ft., making them amongst the tallest trees in the British Isles. The cone is about 7cm. long.
Bearing in mind the size of a giant redwood Sequoiadendron giganteum, the tallest of all trees, its cone (above) is disappointingly small - only about 4cm. long. These trees have thick, fibrous bark that protects the living tissues below the bark from periodic forest fires, whose rising heat opens the cones and allows the winged seeds to spin down into the mineral-rich ash that they leave in their wake. The cones take two years to ripen and can stay on the tree for 20 years in their native California, though they fall much more quickly here.

We only have three native conifers here in the UK and of these only Scots pine Pinus sylvestris carries woody cones. Like many cones, those of Scots pine open when they dry, due to tensions that arise in the shrinking lignified fibres in their woody bracts, allowing the winged seeds to shake out into the breeze. The pictures above and below are of the same cone, wet and dry - a poor-man's weather glass if you keep one outside on a window ledge. This cone is 4cm. long but cone size can be quite variable in this species.

For more posts on this blog on tree ID - buds, bark, flowers or fruits - click here.

Tuesday, November 29, 2011

Roe Deer

This roe deer stood watching us as we walked along the River Tees this morning, from Barnard Castle to Cotherstone. It's just beginning to grow its winter coat, which blended beautifully with the autumn colours in this beechwood.

A little further on we found a doe with is year's fawn, both looking in fine condition at the end of a long, mild autumn when there has been plenty of food available.

Saturday, November 26, 2011

Earthworms- Nature's Ploughs

This is a rather alarming view of a very familiar animal - an earthworm. That's its mouth at the tip. As Charles Darwin observed in his book The Formation of Vegetable Mould, through the Action of Worms, published 1881, 'the whole country has passed many times through, and will again pass many times through, the intestinal canals of worms'. 
This was one of many that I disturbed when I was digging our vegetable garden yesterday. 

Darwin's book - the last that he wrote - remains one of the most fascinating sources of information about these useful animals. In his day there were still many people who treated them as pests, but he confirmed their essential role in maintaining soil fertility. Darwin was an inveterate experimentalist, demonstrating that earthworms swallowed earth 'for the nutritious matter it contains' and finding tiny smooth  stones in their gizzards 'used as millstones' for grinding up buried leaf material. His treatise contains information about their food preferences (he showed that they preferred onion, celery, carrot and cherry leaves above all others) and reports experiments that showed that up to 53,767 worms can live in a single acre of healthy garden soil, that they add fine soil to the surface (via worm casts) at the  rate of between 7.56 and 16.1 tons per acre per year (depending on soil type) and that their constant 'ploughing' of the soil, via tunnelling and feeding, buries objects like large stones at the rate of about 0.2 inches per year.

Worms' bodies are beautifully adapted for tunnelling. The inside of that spindle-shaped body is a fluid-filled cavity which forms a hydraulic skeleton, so that contractions of the circular muscles that run around the segments or the longitudinal muscles between them, acting on the incompressible fluid within, makes sections of the body shorter and fatter or longer and thinner.

Here, contraction of the circular muscles elongates the front segments of the body. You can also see the 'upper lip' (prostomium) of the mouth which, with the aid of powerful pharygeal muscles within, can act as a kind of sucker and allow the animal to grip and drag leaves - and surprisingly large stones used to block its burrow entrance. Those little pores on each segment are the site of retracted bristles.

When the longitudinal muscles contract and the circular muscles relax the body becomes shorter and fatter, filling the tunnel and forcing out short, curved bristles that give the animal purchase on the tunnel walls, allowing it to drag the hind segments forward or resist being pulled out by a predatory bird if caught dangling its tail out of the tunnel - as earthworms are prone to do. 

The bristles are too small to see with the naked eye but you can hear them - put a worm on a sheet of paper and you'll hear them scratching the surface as the worm wriggles. 

Darwin investigated the senses of earthworms in considerable detail, demonstrating that they could detect light but had no sense of hearing, although they were 'extremely sensitive to vibrations in any solid objects' - like soil, for example. His famous description of these experiments in his book are worth quoting in full.

'Worms do not possess any sense of hearing' he wrote. 'They took not the least notice of the shrill notes from a metal whistle, which was repeatedly sounded near them; nor did they of the deepest and loudest notes of a bassoon. They were indifferent to shouts, if care were taken that the breath did not strike them. When placed on a table close to the keys of a piano, which was played as loudly as possible, they remained perfectly quiet'.

He then went on to show that if he moved his pot of worms from the adjacent table onto the piano, they immediately retreated into their tunnels when notes were played, because the vibrations travelled through the piano, pot and soil.

You can download the whole of The Formation of Vegetable Mould, through the Action of Worms from Darwin on-line, here - it's well worth reading.

Thursday, November 24, 2011

Traveller's Joy .... Ecologists' Despair

When people move around they often take plants with them to remind them of their origins. This kind of sentimental attachment to plants has produced some disastrous consequences in various parts of the world. South Western Australia is infested with sweet briar  Rosa rubiginosa, taken there by early settlers as a fragrant reminder of the hedgerows of the 'old country' that they left behind. Similarly, settlers took purple loosestrife Lythrum salicaria to North America, where it has since run riot through wetlands, doing enormous ecological damage. It's commonly the case that European plants that are perfectly benign in their native habitat become botanical hooligans when they're shipped overseas.

This plant, traveller's joy or old man's beard Clematis vitalba is another example of a British botanical export that has run amok in its new surroundings. Traveller's joy was taken to New Zealand in the early years of the 20th. century and is now one of that country's worst weeds, climbing to the tops of trees and smothering native vegetation.
It's not a native species up here in North East England but it is in Sussex, where I grew up, and there it decorates hedgerows with its fluffy seed heads, so when we moved up here thirty five years ago I asked my family to send up some seeds, as a reminder of home. The two plants in our hedge produce plenty of these seed heads that look beautiful amongst the dying leaves, especially when they are back-lit by the low winter sun, and so far there are no signs of the plant spreading in its new surroundings. It really only thrives in limey soils, like those of the chalk downs of Sussex, and our soil here isn't alkaline enough, so I don't think I'll be responsible for a local invasion by this plant any time soon.

I brought this plant up here with me from Sussex too, although it's actually native to North Africa. It's winter heliotrope Petasites fragrans and, true to its name, it blooms from November to February. There are separate male and female plants but only males are known in Britain so there's no chance of it spreading via seeds. It is invasive though. I introduced just one small plant into my garden but it has creeping underground rhizomes and now the clone covers about four square metres, so I'll need to bring it to heel soon. It's not the world's most attractive plant but I grow it for sentimental reasons, because it grew on the roadside leading to our house in Sussex and because it has one distinctive feature that reminds me of childhood. The flowers have a wonderful fragrance of marzipan (though some think it smells of vanilla) and it reminds me of the smell in the kitchen at home at this time of year, when my mother was icing the Christmas cake.

A Quiet Walk.........

I imagine most nature bloggers have their favorite, regular paths on their 'home patch.' There are plenty to choose from in Weardale but for me one of the best is a circular walk that follows the path uphill from St. John's Chapel, alongside Harthope burn. It's  the subject of today's Guardian Country Diary. The burn descends in  series of cascading steps, cutting a ravine that's flanked by a larch plantation, where we recently watched what may well be one of the last red squirrels in Weardale. 

The path emerges through the trees onto the flanks of Chapel Fell, where .....

.... the view westwards towards the upper dale continues to improve as you climb further up the fellside. I'm always struck by how quiet it is up here, once you leave the sound of tumbling water behind. You suddenly become aware of the sound of your own breathing as you labour higher up the hill, and the sound of the wind in your ears. Quietness - or at least freedom from mechanical noise - is a rare commodity these days. There are, of course, plenty of  natural sounds here - the mournful calls of golden plover in spring (especially spooky if its a misty day and you can't see them), wild calls of lapwing and curlew in April, and last weekend...

... our attention was drawn skywards by the mewing of buzzards. No less than eight were circling overhead at one point, drifting slowly down the dale until they disappeared into the blue ....

Sometimes there are shepherds and border collies up here, rounding up sheep, and even falconers that bring their birds up here to train. 

There are other native raptors here too - last weekend, we watched a wandering hen harrier, slowly quartering the rough pastures. 

It's a tough place to farm, a weathered landscape ....

... bearing the traces of earlier generations of farmers ....

The view northwards across the dale reveals farms that are aligned with the natural springs that flow down into the river Wear ....

.... and when you get back down to the bottom of the valley at Daddry Shield you follow the river, through the hay meadows, until you reach the ford and turn back into St. John's Chapel. A perfect Sunday morning walk, in any season of the year.

More pictures of the same walk in another season  here and here.

Tuesday, November 22, 2011

Terrors of the Night

The mild, wet weather seems to have brought an influx of mosquitoes into the house, attracted to the light and entering via windows left open after sunset. Strange how you don't notice them until you get into bed, isn't it? Then the big question is whether it's a biting species of mosquito or a more benign one............ 

 After consulting Keith Snow's Mosquitoes (Richmond Publishing Naturalists' Handbooks No. 14) I'm inclined to think that this one, with its distinctive black and white striped legs, is Orthopodomyia pulcripalpis. He mentions that the females appear to feed on birds - so it's probably safe to go to sleep with one of these in the room - but he does add that "Little is known of adults' ecology and behaviour..." so that isn't completely reassuring. There's another rather similar species called Culiseta annulata which, he says, are "often found in houses where they feed readily on the occupants".
For some high magnification images of the beautiful eyes of mosquitoes, click here.

Saturday, November 19, 2011

Oh, I-do-like-to-be-beside-the-seaside....

Tynemouth this morning: blue sky, blue sea, a bracing breeze, salty air, ships on the horizon, lapping waves, raucous gulls, fish-and-chips for lunch at the Waterfront in North Shields ..... perfect Saturday morning at the seaside.

Wednesday, November 16, 2011

Northern winter moth

Moth identification is not my forte but since there aren't many around to choose from at this time of the year I've whittled down the possibilities and am going to hazard a guess that this might be a northern winter moth Operophtera fagata (but I'd welcome any more accurate suggestions). It was resting on fallen beech leaves in Hamsterley Forest this morning and since beech is listed as a food plant, and since in Waring and Townsend's Field Guide to Moths of Great Britain and Ireland it's described as 'similar to a winter moth, but paler and somewhat silky in appearance..' it seems plausible. Correct ID or not, I really liked the combination of shapes, textures and autumnal colours....

Thursday, November 10, 2011


Rob, over at The Living Isle, on the Isle of Wight, has posted some interesting pictures of wasps visiting ivy flowers , while pictures of red admirals and honeybees on the same plants were posted by Blackbird over on Bugblog recently. Despite a frost earlier in the week, the ivy up here in the North East is still flowering well and attracting the last surviving insects - which are now mostly flies.

Ivy is so common and widespread that we tend to take it for granted but it really is one of the most important plants in the British flora. What other species provides so much nectar and pollen late in the autumn for insects, followed by berries to feed departing migrants in spring - with a dense covering of waterproof leaves through the intervening winter to provide shelter for hibernating insects?

This fly, which is showing a lot of wear-and tear on the trailing edges of its wings, is acting like a living pollination brush. The structure of the flowers, with the anthers elevated above the nectar secreting ovary, pretty much guarantees that the ivy flowers will be pollinated  ....

... as the fly stumble across the flowers, reaching down with its short proboscis, half-blinded by pollen that it's picked up. The strange musty scent of ivy, which has been likened in mouldering papers in damp cupboards, seems very attractve to flies - if you put a cut flower shoot in a room where flies are bouncing against the window, they'll soon turn their attention to the flowers and start to feed.

Tuesday, November 8, 2011

I've Seen a Ghost...

About 50 years ago, when I was a feral 10 year-old growing up in the Sussex countryside, I was mooching through the reed beds at the head of Fishbourne Creek in Chichester harbour at dusk when a large brown bird rose up in front of me and flapped slowly above my head, transfixing me with a penetrating stare of its raptorial eyes. I knew instantly what it was - a marsh harrier - because I'd spent hours scrutinising the pictures in P.A.D. Hollom's Popular Handbook of British Birds in the library - and had the usually schoolboy obsession with rarities. Trouble was, no one would believe me. In those days marsh harriers were rarer than they are today, especially in that part of Britain (where there were, then, some ruthless gamekeepers that shot everything with a hooked beak and proudly hung it all on a gibbet) so all the wildlife 'experts' that I mentioned it to gave me a condescending smile and told me I must have got it wrong. I even began to wonder whether I'd imagined the encounter... but I knew what I'd seen.

I'm sorry to admit, to my shame, that I lapsed into 'wildlife expert' mode a couple of days ago. We were walking up a little valley near St. John's Chapel in Weardale when my wife, who was about ten yards ahead of me, turned and said "Look! A red squirrel". 
Now the last time I saw a red squirrel in the middle section of Weardale must have been about twenty years ago and - apart from a small population right up at the head of the dale, at Killhope (see pictures and post here) - it seems to be generally agreed that they are extinct here.
So my instant reaction was a dismissive "No, it can't be. They're long gone. Must be a grey squirrel with a  tinge of brown fur".

But it was indeed a red squirrel. A ghost from the past - except that it was as large and life and scolding us as it raced from the ground up the trunk of a larch tree. 

So I had to apologise for my shameful scepticism pretty quickly. It reminded me of why I've never like the term 'expert', which all-too-often equates with 'know-all".

Anyway, having got that admission off my chest, isn't this a lovely animal?

As we watched it leap from tree to tree it sent down a shower of golden larch needles every time it landed on a branch.

These are big enlargements of small sections of the whole image,so the quality isn't great, but who cares!

Magnificent ear tufts...

The big question, of course, is where did this animal come from? It's very unlikely that it made it down the dale from the distant population at Killhope - most of the intervening territory is open moorland. There are a lot of predators that could catch and kill it in the open (at one point on Sunday we watched eight buzzards soaring overhead). 
This larch plantation is too small to support a red squirrel population all year-round, but there is another much larger conifer plantation about a mile away, that might conceivably shelter a relict population.
Or maybe this is the result of someone's freelance red squirrel reintroduction programme?

There are no answers at the moment but it was a magical - and, I have to admit - humbling encounter.

Monday, November 7, 2011

Sparkle and Glitter

Last night we had our first hard frost, so .....

..... the strings of pearls of autumn have given way to .....

... the diamond necklaces of winter ....

Thursday, November 3, 2011


If you have a cupboard under the stairs, or kitchen cupboards that have dark, damp corners, then the chances are that you also have some of these silverfish Lepisma saccharina  lurking in them.  These primitive wingless insects belong to an order known as the Thysanura and are often thought of as being living fossils, having first evolved over 300 million years ago. They are covered with silvery scales that are easily detached and they also move fast, which makes them difficult to capture intact; this one has lost part of one of its three tail appendages and also the tip of an antenna. They are most active at night, emerging to feed on whatever organic material  they can find - spilled food, paper, even the glue from cardboard cartons. Sometimes they find their way into baths in bathrooms.

Although silverfish are present in most houses they don’t often produce severe infestations because the females only lay about twenty eggs during their lifetime, hidden in crevices until they hatch. They are, apparently, easy to maintain in captivity and will live for up to five years on a diet of damp paper and a pinch of flour, with regular access to moisture.

The first detailed description we have of a silverfish was recorded in Robert Hooke’s Micrographia or Some Physiological Descriptions of Minute Bodies Made by Magnifying Glasses with Observations and Inquiries thereupon, published in 1665. 

The book contains this copper engraving of the insect, which is of stunning accuracy when you consider that Hooke observed it with lenses that he ground himself for his simple microscope – modern microscopists still marvel at his extraordinary skill and powers of observation. (You can see another example of his skill here).

Samuel Pepys was also mightily impressed and bought a copy of the book on publication, noting in his famous diary on 20th.January 1665took home Hook’s book of microscopy, a most excellent piece’.

Hooke called the silverfish ‘the small silver-colour’d bookworm’ and described, in his elegant prose, how ‘it appears to the naked eye, a small glittering Pearl-coloured Moth, which upon the removal of Books and Papers in the Summer, is often observ’d very nimbly to scud, and pack away to some lurking cranney, where it may the better protect it self from any appearing danger. Its head appears big and blunt, and its body tapers from it towards the tail, smaller and smaller, being shap’d almost like a carret’.

He described how it had ‘ conical body, divided into fourteen several partitions, being the appearance of so many shells, or shields that cover the whole body, every of these shells are again cover’d or tiled over with a multitude of thin transparent scales, which, from the multiplicity of their reflecting surfaces, make the whole animal appear a perfect Pearl-colour’ 

You can find pictures and information on the firebrat - the silverfish's larger but less common cousin - here and you can also view some other animals that share our houses with us here and here.

Tuesday, November 1, 2011

Yew Midge Gall

This year some of the yew trees in Teesdale are heavily infested with this 'artichoke' gall, caused by a tiny midge called Taxomyia taxi. This insect has a strange two-speed life cycle. Eggs are laid on the yew shoot tip foliage in late spring, inducing the formation of a swollen terminal bud where they spend the winter. Some emerge as adults in the following year but others, like his one, have slower development and spend a second winter inside an enlarged and more conspicuous gall before emerging as midges two years after the eggs were laid.

Margaret Redfern's recent New Naturalist book, Plant Galls, is a mine of information on the strange world of these plant-insect interactions.