Saturday, August 29, 2009

Purple Haze

Heather, or Ling, Calluna vulgaris
Heather moorland
The heather moorlands in the North pennines are just about at their best now, with hundreds of acres of hillside clad in billions of tiny purple flowers. Although heather moorland looks like a uniform sea of purple there are three different species that contribute to the purple haze that shimmers on the fellside on a hot summer afternoon. Cross-leaved heath (Erica tetralix) grows in the boggier patches and flowers first, followed by bell heather (Erica cinerea) and ling or true heather (Calluna vulgaris) which both grow on drier soils. Flowers of the first two species are distinctly bell-shaped and in bell heather they’re concentrated in clusters at the shoot tips, whereas in cross-leaved heath they tend to be distributed more uniformly down the stem. The leaves of cross-leaved heath are distinctive too, arranged in whorls of four. Ling, in the close-up photograph above, is far the commonest of the three and has more densely packed, paler, smaller flowers distributed over long lengths of stem, with leaves that are tiny in comparison with the other two species. The heather moorlands of the north Pennines are skilfully managed by cyclical of burning in strips, removing the old, moribund heather. The fast-moving fire burns away the old heather without killing the roots, which then regenerate tender new shoots that are an important element in the diet of red grouse. Burning in strips creates a varied habitat with a mosaic of age structures, providing a habitat for a wonderful range of birds, insects and reptiles............more of them anon.

Wednesday, August 26, 2009

Bedeguar Galls

The strange object in the upper image, looking like an alien visitor from outer space, is a young bedeguar gall caused by the gall wasp Diplolepis rosae, which lays its eggs in the dog rose host and triggers this proliferation of tissue. When fully grown, like the example in the bottom image, the core of the gall contains up to 60 chambers, each with a wasp grub inside and enclosed in a mass of mossy grown. These galls are just beginning to become conspicuous on rose bushes around here and by late September they’ll reach their full size. As winter progresses all that spectacular mossy red growth withers but the larvae inside continue to feed through the early part of the winter, pupate and hatch in May as adults that lay eggs in unopened leaf buds. A wide range of other organisms take up residence in the gall, alongside the gall causing organism. Some are inquilines – opportunist squatters that take up residence in the gall tissue - while others are parasites that lay their eggs in the Diplolepis rosae larvae. There are even parasites that attack the parasites – hyperparasites – in these complex communities. You can find more information on this gall, the insect that causes it and the ‘hangers-on’ at

Monday, August 24, 2009

Thick-headed Flies

Conops quadrifasciata pairs remain together like this for some time after mating has taken place, and take to the air in unison

Females have a more slender abdomen that's sharply curled under at the tip

The exceptional width of the male's head is visible here. Maybe it's because the female's vision is obscured by the male above, so he has to act as look-out for both of them

These flies, mimicking wasps and linked together during mating in characteristic biplane arrangement, as thick-headed flies Conops quadrifasciatus that I found in a field of ragwort in Durham. The bottom photo shows the broad head which gives these insects their common name. They’re parasites of bumblebees, laying eggs on the adult bees which are then literally eaten alive by the parasitic larvae. One study carried out in Switzerland and published in 1990 found that almost 35 per cent of workers of early bumblebee Bombus pratorum and common carder bee B. pascuorum sampled in August contained this parasite’s pupae. At this time of year there are always a lot of sleepy-looking bumblebees apparently resting on flowers and showing little sign of feeding, and many of these are likely to be suffering from parasites, including conopid fly infestations. There’s no doubt that habitat destruction has been a major factor in bumblebee decline, but it’s also true that parasite infestations can have a very significant impact on local populations too.

Crane'sbill Catapults

Meadow Crane'sbill catapults discharged
Meadow Crane'sbill catapults primed and ready to go

The meadow crane’sbill Geranium pratense in my garden (see has now run to seed and is using its natural catapult mechanism to hurl seeds around the flower borders. There are five seeds, each inside an ovary that splits open, arranged around the bottom of the central ‘beak’ of the fruit and connected to it by long strips of dead cells that become tensioned like springs as they dry out. When the tension reaches a critical point each ovary breaks free and is flicked upwards violently by its ‘spring’, hurling out the seed – just like a rock launched from a Roman siege catapult. It’s a highly effective mechanism – from one original plant, I now have meadow crane’sbills all over the garden. The seeds of this species have a hard, water-repellent outer coat and are slow to germinate, so if you want to raise it from seed gently abrade the seed coat with a piece of sandpaper, then it will germinate very quickly.

Saturday, August 22, 2009

Aromatic Umbellifers

Hogweed Heracleum sphondyliumSweet cicely Myrrhis odorata

The carrot family (Umbelliferae) includes several species with seeds that contain aromatic compounds that are used as flavourings – cumin, fennel , celery and caraway are notable examples. The bottom picture here shows the ripe seeds of sweet cicely Myrrhis odorata, an umbellifer which was once cultivated for its aniseed flavour and used to sweeten puddings, in the days before sugar was a cheap, easily available commodity. The species is widely naturalised in North East England and every part of the plant has an aniseed aroma. Apparently, the seeds were also once used to make a pleasantly aromatic floor polish. The top photo is of hogweed Heracleum sphondylium seeds, which are not edible but do contain a fruity, aromatic oil that has a very refreshing scent – try crushing some ripe seeds between finger and thumb and you’ll see what I mean. The oil is concentrated in those four dark brown stripes, which are oil glands.

Thursday, August 20, 2009

Mountain Ash Berries – Food for Birds and People

Summer is far from over (I hope!), but when mountain ash Sorbus aucuparia berries ripen you known that autumn is fast approaching. They don’t last long – blackbirds strip the trees very rapidly. There is persuasive scientific evidence now that the fruit juice and pulp of Sorbus fruits inhibit the germination of the seed inside, but passage through a bird’s gut removes this obstacle, and there’s also evidence that a bird’s digestive enzymes weaken the seed coat, making germination easier. While the fruit is being digested the seeds can be carried long distances from the parent plant before they’re voided, so it's no wonder this attractive tree is so widely distributed. Mountain ash berries also feature in the human diet, indirectly. Check out the ingredients in your toothpaste, low calorie food or most diabetic food products and you’ll probably find that they contain the sugar alcohol sorbitol, named after the Latin generic name of the plant that it comes from. Sorbitol was discovered in mountain ash berries by a French chemist back in 1872. It’s used as a sweetener in toothpaste because bacteria in the mouth can’t feed on it, so it doesn’t contribute to tooth decay. It’s used in diet foods as a supplement to artificial sweeteners because it has a lower calorific content than glucose.

For more posts on tree ID click here

Monday, August 17, 2009

A Galling Mystery

Silk Button galls caused by Neuroterus numismalis
Silk button galls caused by Neuroterus numismalis, spangle galls caused by N.quercus-baccarum and a spherical gall caused by Cynips divisa

An artichoke gall caused by the wasp Andricus fecundator

Plant galls are breeding chambers produced by insects – often gall wasps – that lay their eggs in the plant’s buds and leaves and induce the plant to change its pattern of growth. Typically, galls develop a hard protective casing lined with feeding tissues for the developing grubs inside. Pictured here are four different galls, all on the same oak twig, produced by four different but closely-related gall wasps. The large, scaly flask-like object is an artichoke gall, produced by the gall wasp Andricus fecundator. The middle image shows a leaf with three different gall types: disc-shaped spangle galls, cause by the wasp Neuroterus quercus-baccarum; a spherical gall caused by the wasp Cynips divisa; and the exquisite silk-button gall caused by Neuroterus numismalis, also shown in the top photo. The growth of each was triggered by a substance that was injected into the leaf tissue at the same time that the eggs were laid, redirecting the normal pattern of cell growth to produce a species-specific gall. So exactly how does each different gall wasp manage to modify its host’s growth to produce its own, unique gall type? Your guess is as good as anyone else's – so far, no one has fully explained the detailed processes involved. For more about Britain's plant galls, visit the British Plant Gall Society web site at

Saturday, August 15, 2009

Pine Plantation Ladybirds

I came across these two ladybird species on the edge of a Scots pine plantation in Weardale this afternoon, where they sunning themselves on fence posts. The top pair of pictures shows an eyed ladybird Anatis ocellata and the lower pair shows the striped ladybird Myzia oblongoguttata. Both tend to be restricted to conifer plantations, where they feed on the aphids that often infest young pine shoots. The fortunes of ladybirds have waned in recent years but in 2009 I have seen more species and more individuals than for the last two wet summers. Thanks to the dedication of the late Mike Majerus, Professor of Evolution at Cambridge University , who enthused the public and particularly children about identifying and recording these useful beetles, we now have a much better understanding of ladybird distribution, which will help in monitoring the impact of climate change and threats from the introduced, predatory harlequin ladybird. Mike Majerus, who wrote a New Naturalist volume on ladybirds sadly died earlier this year at the age of only 54. You can read about him at
You can find out more about helping with the Ladybird Survey, and download a photographic ID chart, at

Thursday, August 13, 2009

A Lost World

( These fossil corals are in the drystone wall near the Packhorse Bridge that you can see in the bottom photo at

Hard to believe at first sight, but the limestone ridges in Ravenstonedale in Cumbria that the kestrel (in the bottom photo – click to enlarge) was hunting over were once the beds of warm shallow seas somewhere near the equator back in the Carboniferous period, over 280 million years ago. The evidence is there to see in the form of fossils in the drystone walls, built from limestone boulders, that criss-cross the valley that Scandal Beck has carved out from the limestone. The fossils in the stones are corals called Siphonodendron, whose tentacles would have swayed in ocean currents. At the time when these animals were alive small early reptiles were beginning to evolve and giant dragonflies hunted through steamy swamps. The first flowers, that are such a conspicuous feature of these limestone grasslands today, would not put in an appearance for another 150 million years.

An Unusual Late-Summer Succulent

This attractive late summer wild flower is orpine Sedum telephium, which is a rather uncommon native here in North East England. Like all Sedum species it has succulent, water retentive leaves and looks more adapted to life in Mediterranean regions than at these latitudes but, unusually for the genus, it’s also quite at home in shady places. This plant was growing at the base of a hedgerow in the Derwent valley, where I have known it for over 20 years. Orpine is closely related to the garden ‘ice plant’ Sedum spectabile from China and Japan and sometimes forms hybrids with it. Most records for the plant tend to be close to habitation and it’s difficult to be sure whether the plants in question are genuinely wild or whether they are descended from plants that were dug up, cultivated and have since escaped back into the wild and are establishing new populations, perhaps even carrying S.spectabile genes if they have hybridised in gardens. It’s probably one of a number of native species, like primroses and columbine, where there has been regular interchange between gardens and the wider countryside.

Monday, August 10, 2009

Holy Fire

These sinister-looking little objects, shaped like claws and growing amongst the florets of cock’sfoot grass, are the fungal fruiting bodies of ergot Claviceps purpurea. This is a species with a notorious history, that contains toxins causing two forms of a disease called ergotism in those who eat rye grains contaminated with the fungus. Alkaloids in the fungus cause contraction in the muscles lining minor blood vessels and capillaries, so that the body’s extremeities are starved of blood, wither, develop gangrene and drop off. Convulsive ergotism causes pins-and-needles symptoms known as formication, a feeling that swarms of ants are running around just below the surface of the skin, in addition to violent convulsions. The fungus also contains compounds akin to LSD, causing delusions; people affected have been known to throw themselves out of windows, in the belief that they can fly. Ergotisn was rife in the Middle Ages amongst people who mainly ate rye bread, this cereal being particularly susceptible to attacks by the fungus. Then, the disease was known as ‘Holy Fire’ or ‘St. Anthony’s Fire’. Like many poisons, the active compounds in ergot have medicinal uses and the fungus was once deliberately cultured to produce drugs that induce muscular contractions and induce childbirth. Ergot is quite common on wild grasses at this time of year, particularly around here on cock’sfoot grass and false oat grass. These specimens were photographed in the Derwent Valley on the Durham/Northumberland border at the weekend. It infects a wide range of species and a few years ago I saw some particularly large specimens growing in the florets of cord-grass (Spartina) on the salt marsh at Grange-over-Sands. Only a tiny fungus, but one with a fearsome reputation and an interesting history.

Sunday, August 9, 2009

The Scent of New-Mown Hay

Large swathes of North Pennine landscape have been converted into green corduroy over the last week, with hay-making in full swing and long windrows of hay drying in the sunshine. It’s been pretty good haymaking weather. Gone are the days of turning hay by hand but one thing never changes – the fabulous sweet smell of new-mown hay drying in the sun.

Saturday, August 8, 2009

Scotch Argus Butterflies South of the Border

Smardale Gill National Nature Reserve, between the village of Ravenstonedale and market town of Kirby Stephen in Cumbria, is one of my favourite reserves, not least because it’s one of only two locations in England where you can see the Scotch argus butterfly. There were scores of them on the wing when we visited earlier this week – some newly emerged, others looking a little weather-beaten. Fresh specimens, which are the colour of dark chocolate, have a lovely velvety texture. The top photo shows the view northwards, towards the old railway viaduct that crosses the valley and now carries a footpath through the wooded part of the reserve. The bottom photograph shows the view to the south, with the packhorse bridge over Scandal Beck and the Howgills in the distance. Between the two lies a steep-sided valley with limestone grassland and a superb flora, that includes fragrant orchids, rock-rose and Jacob's ladder. The reserve is managed by the Cumbria Wildlife Trust and you can read more about it at

Friday, August 7, 2009

Low-Visibility Toad

This toad was so well camouflaged that we almost trod on it when it wandered across our path in the Bishop’s Park in Bishop Auckland. The flash photos (top) have more impact but the natural light image gives a much better impression of the amazing match between the toad’s warty skin and the pebbles on the path – dangerously effective camouflage if there are humans with big feet stomping around...

Thursday, August 6, 2009

An Industrial Legacy

Just south of Seaham on the Durham coast (see there’s a little bay called Hawthorn Hive, reached by a steep cliff path. The Magnesian limestone is constantly eroding here, creating small landslides that bring down the flora and fauna from the cliff tops to beach level. There it’s completely sheltered from the south-westerly winds that blow across the cliffs for most of the time, so the display of wild flowers and butterflies at the back of the beach is simply wonderful. Pictured here, from top to bottom, are carline thistle, yellow-wort and rest harrow. This is one of a number of delightful bays along this coast that were once used for dumping colliery waste, that are well on the way to being fully restored to their former glory, but ironically the narrow zone of biodiversity at the base of Hawthorn Hive’s cliff depends on past industrial pollution. Here coal dumping created a raised beach that stops the waves from reaching the base of the cliffs (bottom two photographs). With rising sea levels, once the sea finally sweeps away the last of the colliery waste (and it’s eroding quite rapidly now), the days of the present cliff base flora and fauna will be numbered. There’s a little more about this at

Wednesday, August 5, 2009

Harebell Sex-Change

Over at Stand and Stare ( Nyctalus has recently been extolling the virtues of The Humble Harebell. It’s worth taking a close look at harebell flowers because they have a really neat fail-safe method of ensuring that they’re pollinated. When the flower is still in bud the style, with a closed stigma at its tip, is surrounded by five stamens that begin to shed pollen. As the style - which is hairy on the outside- elongates inside the bud it forces its way through the tube of stamens surrounding it, sweeping the pollen from their surface. So when the flower opens it looks like the one in the bottom photo, and any insect forcing its way down to the bottom of the harebell bell will pick up pollen from the outside of the style. At this stage the flower is functionally male, dispensing pollen. Once the pollen is all gone the tip of the style splits into three lobes that curl back (top photo) and now the flower has effectively become female, ready to receive pollen on one of those three stigma lobes from a visiting insect. But what if no pollen-laden insects turn up? No problem; those stigma lobes just keep curling back until they pick up any residual pollen that’s still left on the outside of the style, so the flower self-pollinates. Harebells are quite easy to grow from seed and if you do raise some you’ll see why their Latin name is Campanula rotundifolia, even though the plant has long, grass-like leaves: the leaves in the seedling rosette are indeed rotund.

Tuesday, August 4, 2009

Still Clinging On: Durham's Red Squirrels

The North of England Lead Mining Museum at Killhope in Upper Weardale ( is a wonderful place to learn more about what must have been one of the toughest ways to earn a living yet devised, hacking lead ore out of the Pennines. The fully restored mine and lead processing equipment, including a giant overshot water wheel, and the exquisite collection of mineral crystals extracted from local mines, are just a few of the delights that the museum has to offer. In the spruce plantation behind the mine you can still watch red squirrels at close quarters, at two feeding stations that have been set up there. They are probably extinct elsewhere in County Durham but a small population still thrives here. During our visit yesterday we watched four red squirrels , including this almost white-tailed example which is typical of our native sub-species – re-introduced populations of European origin tend not to display this distinctive feature. A couple of the squirrels still carried their long ear tufts, which red squirrels are supposed to lose in summer; presumably they hadn’t read the ID guides. If you visit Killhope, which opens at 10am., head straight for the squirrel hides, before the visitors to the mining museum start exploring the woodland trail, and you’ll stand the best chance of seeing these fast-disappearing animals.