Tuesday, April 28, 2015

Primslips or Cowroses?

The wild flower conservation charity Plantlife is conducting a poll to find Britain's favourite wild flower and the primrose Primula vulgaris is a strong contender to take the title. Currently it is in top position in Scotland and Wales, second in England and third in Northern Ireland.

Primrose is primarily a plant of woodland edges, glades and hedgebanks, growing best in dappled shade and in moist soils. It's also a very variable plant, thanks to its breeding system, where there are two forms of flower - pin-eyed and thrum-eyed - with the stamens and stigma arranged in a way that ensures cross pollination when insects travel from plant to plant. 

Pin-eyed flowers have their stigma at the top of the floral tube and their stamens lower down, whereas ...

... thrum-eyed flowers have stamens at the top, with the stigma hidden underneath them.  It's an arrangement that maximises the chances of cross-pollination, reinfornced with an incompatibility system where the flower's own pollen will not normally germinate on its own stigma. The cross-pollination that this enforces generates genetic variability within the population - compare the broad-petalled flower above with ....

.. this one which has much narrower petals.

Primrose also readily crosses with .....

....... cowslip Primula veris wherever the two species meet, typically where woodlands meet the pastures that are the favoured habitats of cowslips. 

Populations of false oxlips, the natural hybrid between the two species, show almost every grade of intermediate form between pure cowslip and pure primrose..... with what you might call primslips and cowroses in between!

Cowslips typically have these small, intense yellow, downward-pointing flowers whereas .... 

..... false oxlip flowers tend to point outwards or even upwards and are larger and paler coloured. The false oxlip - with an injection of genes from a cross with at least one other more colourful European species ....

....... is the ancestor of the gaudy, very popular polyanthus that is the mainstay of so many municipal bedding schemes in spring.

Saturday, April 25, 2015

Eight kinds of cuckoo pint

Lords-and-Ladies aka cuckoo pint aka Arum maculatum is a familiar enough plant, but one that is more variable than it might seem, because....

Some plants have a yellow spadix (the club-shaped bit in the centre) and ....

... others have a purple spadix. Then there's the leaves .....

... which in some plants have dark purple spots ......

..... and in others are plain green. The frequency of leaf spotting depends on location, with purple spotted leaves being much commoner in central and southern England than in northern England. 

All combinations can occur but plants with yellow spadices and spotted leaves are rarest (around 9% according to C.T.Prime Lords and Ladies [New Naturalist special volume] 1960).

So that's two major variable characters - and there's another one. For that you need to look at the way that the base of that cowl-shaped spathe is coiled. It can be........

...... clockwise, as seen from above .....

...... or counter-clockwise, as seen from above

So, altogether there are eight possible combinations of these characters.

For more about the botany of Arum maculatum, click here and here

Tuesday, April 21, 2015

Kittiwake cacophony

The Tyne Bridge in Newcastle, and the buildings around it, are famous for hosting the largest inland breeding colony of kittiwakes in the world, offering unrivalled opportunities to watch the behaviour of these birds. The noise can be deafening. These two were exchanging greetings today. 

Click here for more about the Tyne Bridge kittiwake colony - and watch a film about these wonderful birds by Cain Scrimgeour

Monday, April 20, 2015

Woodland walk along the river Tees that J.M.W.Turner trod 200 years ago

This is the view of the river Tees from Abbey bridge near Egglestone, on a tranquil spring day. When the snow melts in Upper Teesdale this becomes a raging torrent, roaring through the rocky gorge. 

The woodland on the steep banks of the river here is exceptionally beautiful in spring, carpeted with wild flowers. Last week wood anemones were the star of the show; next week the bluebells will take over.

Fallen trees are left to gently decay and often develop their own 'garden' of flowers as they rot - like this one with a flora of wood anemone, ramsons and herb Robert.

Last week the bluebells had just begun to flower but it will be early May before the tree leave canopy begins to close over them. The fully-grown trees are mostly sycamore and oak.

The path winds through a dense carpet of wood anemones, high above the river.

Wood speedwell Veronica montana

When we arrived there was still a chill in the air and dew on the leaves, so the wood anemone flowers were all nodding downwards ...

..... but by mid-morning, as the sun climbed higher in the sky, they turned to face it.

This wood anemone had purple leaves.

Some early wild cherry blossom, hanging over the river.

Wood sorrel, nestling against a moss-covered tree base. The leaves fold down at night, like triangular tents.

Beyond the woodland the path passes through pastures, with ground ivy Glechoma hederacea flowering in the shelter of a dry stone wall.

Last week the first influx of warblers arrived, with this willow warbler and blackcaps singing

Last time we passed this way the elms were just coming into flower. Today their clusters of seeds were well-formed.

A bee-fly, a parasite of mining bees, sunbathing in a clearing.

Crane-flies mating.

A comma butterfly soaking up the spring sunshine after a long hibernation.

In 1816 J.M.W. Turner must have walked this footpath and perhaps sat somewhere near here to sketched this scene, at the confluence of the river Greta and the river Tees, which he painted in 1818. I like to think that perhaps he sat under this ancient oak, which would have been more youthful then, to view the scene, which you can see in his painting by clicking here.

Saturday, April 18, 2015

Nuthatch home improvements

We spotted this nuthatch, busy working on a nest hole in an old oak tree, when we were out walking in Teesdale last week.

Nuthatches usually nest on tree holes, selecting one that has a slightly larger opening than they need and then partially blocking up the hole with mud. We watched it make several trips down to the edge of the river Tees to collect the necessary building material but ....

.... it also came back with water and then seemed to regurgitate it as it entered the nest - you can see droplets hanging from its beak in this rather blurred photo. I suspect that what it was doing was softening the mud that was lining the entrance but had dried in the sun, because then ....

..... it entered the nest hole and then squeezed out again through the muddy aperture ....

..... using its body to mould the perfect size of entrance hole.

Thursday, April 16, 2015


Today's Guardian Country Diary is about the return of marine life to the Durham coast at Dawdon, where coal mining waste was dumped onto the beach until Dawdon colliery was closed in 1991. An underwater survey by divers at that time found half a metre of coal silt on the sea floor at Noses Point (in the background of this photo) and water that was so turbid that it was impossible to see any marine life.

Since then the Turning the Tide campaign has cleaned up the beaches, to the point where this beach was recently described in the Guardian as one of the best lesser-known National Trust beaches in the UK 

Click here for more pictures and information about the restored coastline here.

Meanwhile the waves have done their work offshore, washing away the coal spoil, so now it's a beach where you can go rock-pooling again. We found this shore crab amongst the rocks near Noses Point. The pointed abdomen under its body indicates that it's a male.

Catching a shore crab took me back to childhood rock-pooling days, and learning to pick up an angry crab between finger and thumb on either side of the shell. That armoured carapace protects the crab from predators but prevents it reaching above its shell with those powerful nippers. This method of holding them works well with shore crabs but from painful experience I've learned that this is less successful with velvet swimming crabs whose nippers seem to be better articulated and can reach back to deliver a very strong pinch.