Whiskers and Hairs

Some pond margins around these parts are taking on a distinctly whiskery look at the moment. After remaining intact all winter, the club-shaped seed heads of reedmace Typha latifolia are finally disintegrating, sending out clouds of plumed seeds just when cotton-sedge Eriphorum angustifolium is coming to the end of its flowering period. The white tassels on cotton-sedge are formed from bristles around the tiny flowers and these elongate once the flowers are pollinated and the seeds begin to develop. C. Pierpoint Johnson’s snappily titled Useful Plants of Britain and Ireland: A Treatise upon the Principle Native Vegetables capable of application as Food, Medicine, or in the Arts and Manufactures, published in 1863, records some interesting folk-uses for these plants. Apparently coopers used to sandwich reedmace leaves between the staves of barrels, to render them watertight. The author also reported recent attempts to use cotton-sedge 'hair' as a substitute for imported cotton and described how, although the spun thread was ‘very tolerable’ the fibres are more brittle than genuine cotton. Enthusing on its potential, Pierpoint Johnson went on to predict a bright future from this by-product of Britain’s bogs: “Some very fine cloth was made a short time ago .... with this vegetable hair,” he reported and speculated that “as it can be collected at very low cost, it is not improbable that it may eventually be brought into extensive use”. Another of those Tomorrow’s World inventions, then, that never made it into production.

Serpents and Vampires

It always seems to me that there’s a hint of menace in the way that bracken fronds erupt through the soil in spring. There’s something of the serpent about them and it wouldn’t come as a complete surprise if they hissed as they straightened their stems towards the sun. As in many other parts of the North Pennines, large patches of hillside above Tunstall reservoir in Weardale (bottom picture) are covered in this fern, that’s expanding its canopy of fronds now. Part of the fern’s success comes from the fact that it’s loaded with toxic compounds, so very few insects will feed on it, but other plants do flourish in the boggy patches amongst its uncurling stems in early spring - including this lousewort whose attractive pink flowers belie a rather gruesome botanical trait. Lousewort Pedicularis sylvatica is a partial parasite on grass roots. Below the surface it has plugged itself into the root systems of surrounding vegetation, siphoning off their water and nutrients: lousewort is a vegetable vampire.

Distant Drumming

At this time of year you can’t walk far in the upland areas of Weardale and Teesdale without hearing the strange bleating sound of snipe drumming. Flying around their territory in wide circles, perhaps a quarter of a mile across, they repeatedly go into power dives and splay out a pair of feathers on the leading edge of the tail. Air rushing over the feathers produces a weird reverberating sound. This bird was flying far too high and fast for a really clear photograph but you can see those splayed out tail feathers quite nicely. You can heard recordings of the sound by visiting here

http://www.guardian.co.uk/environment/2008/jun/06/wildlife.birdsong

and here
http://www.rspb.org.uk/wildlife/birdguide/name/s/snipe/index.asp

Only 218 days until Christmas

They say that a heavy crop of holly berries in autumn is a sign of an imminent hard winter but what it really signifies is that the tree experienced favourable pollination conditions back in the spring. There are separate male and female holly trees so they need to be cross pollinated by insects (usually flies and perhaps small bees), so good weather for pollinator activity means a heavy berry crop come December. These are female holly flowers and their green centre (the ovary) will start to develop into the scarlet berry once an insect arrives, attracted by the nectar that's visible in this picture, and deposits a load of pollen on that sticky stigma.

Bird’s-eye Primrose

Between Teesdale's High Force waterfall (see yesterday's posting) and the waterfalls at Wynch Bridge (bottom picture here) you can also find the diminutive bird’s eye primrose Primula farinosa, growing in shallow patches of soil on wet rock ledges close to the river. Their small leaf rosette and flower stalk is covered with waxy scales, known as farina, which make the plant easy to identify even when it isn’t in bloom. The flower shape, size and intensity of colour is variable in this species because, like the common primrose, there are two different forms of flower in the population, which ensures that the plants are cross-pollinated rather than self-pollinate, and so produce very variable offspring. Take a close look at the flowers in the top and second from top pictures here (double-click the image for a larger view). In the top plant you can see a ring of five stamens, which dispense pollen, at the top of the flower tube. The stigma, which receives pollen, is hidden way down inside the floral tube. In the plant in the second picture the single stigma is at the mouth of the flower tube and the stamens are hidden from view within. This differential positioning of stamens and stigmas in different individuals ensures that visiting insects cross-pollinate the flowers.

Double Dumplings

Teesdale is famous for its flora, notably its spring gentians (see earlier post), and after the gentians have faded they are followed by a host of other rare or uncommon species that makes the dale a favourite destination for botanists. Just now the globe flowers Trollius europaeus are at their best, in bloom all along the Tees downstream from High Force (bottom picture). The flowers of these relatives of the buttercup, about the size of a golf ball, form a sphere of petals with a gap just large enough for flies to crawl in and pollinate the flowers. This was once a much more widespread species in wet pastures, until eliminated by the application of fertilisers that favoured grasses at the expense of flowering herbs. I’m told that locally they are traditionally known as ‘double dumplings’, although I have to confess that I’ve never heard anyone actually call them that. I first learned to identify wild flowers in the early 1960s by collecting the tea cards with illustrations by Charles Tunnicliffe, that used to be between the wrappers of Brooke Bond PG Tips tea. Globe flower was the only card I needed to complete the set of 50 British wild flowers and despite imploring every member of the family to drink as much tea as possible I never found it. It was 1975 before I actually got to see the real flower in Teesdale, and it's good to report that they are still thriving where I first saw them.

Beetle Gymnastics

I found this little click beetle Athous haemorrhoidalis in a nettle patch and as soon as I disturbed it, it tucked its legs under itself and became completely rigid. When I flicked it onto the palm of my hand it performed its party trick; feigning death then performing energetic gymnastics. The shape of the beetle means that when it folds its legs under itself it automatically rolls onto its back, feet in the air, and there it lies, playing possum, with its body slightly arched. There’s a peg that forms a frictional link between its thorax and its wing cases and tension develops between the two parts of the body as it flexes its muscles, until the peg finally slips and the beetle straightens itself with explosive force, somersaulting into the air and away to safety. The grub of this insect is the wireworm, notorious destroyer of potato crops, but in the wild the adult is a rather endearing insect.

Click here for YouTube video of a click beetle 'clicking' 

Meadow foxtail

For hay fever sufferers the season of misery has arrived, and this is one of the culprits – meadow foxtail grass Alopecurus pratensis. The flower spikes produce their feathery stigmas from each floret first (bootom picture), then the dangling stamens are produced from the top of the flower spike downwards (top picture), releasing clouds of minute pollen grains as they split open. Some pollen grains are filtered out of the air by those feathery stigmas, which you can see under the microscope at my other bog Beyondthehumaneye

Meadow foxtail is very similar to Timothy grass Phleum pratense and the easiest way to tell them apart is by flowering time – Timothy doesn’t begin to flower until July, after spring-flowering meadow foxtail has finished.

Roe Deer Shedding Velvet

Luck was with us this morning, when we were out walking in the Derwent Valley hear Edmundbyers. We managed to get within about 50 metres of this roe buck that was sitting on the hillside enjoying the sunshine. He didn’t seem to notice us approaching downwind, with our silhouettes below the skyline. His coat looks a bit mangy but I think that’s because he’s shedding his long winter coast and acquiring his shorter summer pelage, but the really interesting features are his antlers. He would have shed the old antlers by Christmas and has now grown a new set. One is still covered in skin (‘velvet’) but he’s very recently rubbed the skin off the other, against the bark of the tree probably, and it’s still covered with fresh blood (double click the top image for a larger image, that makes this clearer).

Wall Butterfly Behaviour

I’ve been watching wall butterflies lately, and their behaviour is fascinating. Have you noticed how, when they land, they fold their wings and shuffle around until their vertical wings are exactly parallel with the sun's rays – like the butterfly in the bottom photograph? I used to think this was some kind of defensive behaviour, so that their well camouflaged wings and body cast the smallest possible shadow. It's certainly easy to lose sight of them when they do this and if you look away they're hard to spot with their wings folded. But now I'm not so sure - I think the reason for this might be more subtle. When they orientate themselves like this it means that when they open their wings (see middle photograph) to bask their wings are at right angles to the incoming sunshine and so are perfectly positioned for absorbing the maximum amount of solar radiation. Maybe this is dual purpose behaviour and there's a grain of truth in both theories. I imagine the butterfly can tell, after it first lands, when its wings are aligned perfectly parallel to the sun’s rays because then neither eye would be shaded by the wings. They do seem to be very aggressive butterflies. The males that I’ve been watching patrol a well-worn footpath beside a hedge, engaging in brief aerial dogfights with rival males before seeing them off the premises. Courtship is an elaborate affair too. When a female arrives on the scene she indulges in a lot of wing vibrating, which I guess might be to drive off the volatile come-hither chemicals called pheromones that butterflies are known to use to attract a mate. The male flies around her and lands facing her, both insects with their wings outstretched, and them he seems to head-butt her and contact between their antennae takes place. Then I accidentally scared them both off (top photograph), so I don’t know what happened next................(the male is the settled butterfly on the right, with the broader diagonal dark brown stripe on the forewings)

Horse Chestnut Traffic Signals

Newly-opened horse chestnut flowers have a yellow spot on the petals, that turns red once the flower is pollinated. More than half the flowers in this photograph seem to have been pollinated, probably by bees seeking nectar that apparently contains a high concentration of sugar in horse chestnut. I recall reading somewhere that this floral colour change is the tree’s way of telling bees not to waste their time visiting flowers that have already been visited and pollinated. The theory was that this works because bee eyes can see yellow but are well known to be relatively insensitive to the longer-wavelength red end of the spectrum. So this is horse chestnut’s traffic light signalling system – conspicuous yellow for ‘proceed’ and inconspicuous red for ‘don’t bother’. I’ve never see any published scientific evidence to back up this plausible but possibly apocryphal story, but with the aid of a decent pair of binoculars it shouldn’t be difficult to see whether the bees do visit the red flowers......

Buttercups: three easy species

All three common species of buttercup are now in flower now on my patch, making them easy to tell apart. Bulbous buttercup Ranunculus bulbosus is the easiest – just look at the sepals below the cup of petals. In this species the sepals bend back and touch the flower stalk (top picture). That leaves creeping buttercup Ranunculus repens and meadow buttercup Ranunculus acris, whose green sepals both support the cup of petals. For them, just take a close look at the flower stalk. In creeping buttercup (middle picture) it has ridges and furrows, whilst in meadow buttercup (bottom picture) it’s smooth and more or less round in cross section.

Solomon’s Seal Fate Sealed

The patch of Solomon’s seal Polygonatum x hybridum in our garden is just coming into flower, looking immaculate after a light shower of rain, but within about a month its leaves will be reduced to skeletons. Yesterday I watched the current generation of Solomon’s seal sawfly Phymatocera aterrima emerge from their pupae in the soil and begin to climb the stems, with the sawflies' wings still not fully expanded. Within five minutes the males had found the females and they were mating. Within fifteen minutes the females were laying eggs in the leaves. Every year the larvae that develop strip away all the leaf tissue but there doesn’t seem to be any fatal long-term consequences for the plants, which has been spreading steadily in the flower border for the last ten years. The top picture is the sawflies'-eye view of the plant arching overhead, as they emerge for another breeding season and the picture below......


 

...... shows their highly destructive larvae at work.

Fulmars and Gorse

We spent the afternoon on the Northumberland coast, setting out to walk from Craster (after lunch in the Jolly Fisherman) to Howick, but only made it half way before the weather turned nasty. We left the pub in bright sunshine but there were already dark clouds on the western horizon. The display of gorse along this stretch of coastline at the moment is stunning – it’s so bright you could get a suntan just from looking at it. Its coconut scent is wonderful, although you needed to get pretty close to appreciate it today, with a strong, blustery wind blowing its fragrance out to sea. The kittiwake colony at Cullernose point was a cacophony of birds, perched on their narrow nesting ledges, but it was the fulmars that I really wanted to photograph. If ever there was a bird that seems to exalt in its power of flight, surely it’s this one, gliding along the edge of the cliffs with scarcely a flap of its wings, effortlessly riding the updraft. They passed so close that we could see the turbulence over their wings ruffling their feathers; too close most of the time, whizzing past so fast that nine out of every ten photographs were out of focus. I could watch these birds all day – but not today, because then the rain arrived - horizontal, driving rain. We were soaked by the time we got back to the car, but we'll be back.

The Afterlife of Trees

I think it might have been Oliver Rackham, botanist and noted expert on woodlands, who once commented that the only object in woodlands more valuable than a live tree was a dead one, since they host so many species of wood-boring beetles and other insects that breed in dead wood. This ancient beech stump, in Durham University Botanic Garden’s new woodland nature trail, is riddled with emergence holes from insects that have bred in it, but its most conspicuous features are the magnificent specimens of the bracket fungus (Ganoderma sp.) that was almost certainly the cause of its death. This parasitic fungus weakens the tree and infected trunks typically snap somewhere above head height during gales. The fungus is perennial, so each year the bracket develops a new zone of spore-producing tissue around its periphery and generates so many spores that they cover the vegetation below with what looks like a layer of cocoa powder. You can estimate the age of the bracket by counting the number of ‘steps’ on its upper surface; each marks the end of a year’s growth. During their ten years of existence, these brackets must have produced billions of spores. You can read more about the woodland nature trail at http://www.dur.ac.uk/botanic.garden/?itemno=7173

A Plant for all Seasons

Just when everything else is coming into flower, ivy is producing fruits. This is a plant that’s completely out of step with the rest of our flora, flowering in late autumn when almost all other blooms have withered. I can’t think of a better multipurpose plant, from the perspective of all the animal life that depends on it. In spring pheasants, wood pigeons and a wide variety of migrant birds are partial to its berries. In summer its dense foliage offers a well-hidden nest site for birds like wrens. In early autumn its flower buds are the food source for holly blue butterfly caterpillars. In autumn, there's a long-lasting, plentiful supply of nectar and pollen for a last-minute energy top up for hibernating insects, and in winter its evergreen foliage offers a waterproof hibernation site for insects. Add to that the fact that it’s more or less ubiquitous, growing on sand dunes and sea cliffs, in towns, on railway embankments, in woodlands and hedgerows. Is there a more versatile or more useful plant in our flora? I doubt it – but it’s so common that most of the time we don’t give it a second thought.

Looper caterpillar

I found this little green caterpillar, not much more than a centimetre long, dangling from a silken thread under a twig of an alder tree. I gather that a lot of small caterpillars that are hunted by tits and warblers use this as a ‘last resort’ escape mechanism. When I put it back on a leaf it showed two other anti-predator behaviours, first aligning itself with the edge of the leaf and then ‘freezing’, like a tiny green twig. Must be a hazardous life for these bite-sized caterpillars at the moment, when tits have so many mouths to feed.