Stoer Green and beyond in 2021

September 11th 2021

Stoer Green and beyond in 2021

This rich area of common grazings (photo 1) continued to provide surprises during June and July, despite a very dry spring and early summer.

June

On 6th June Bill Badger and Ian took a walk across the Green and along the path above the cliff-tops.  Flowering clumps of thrift or sea pink Armeria maritima were conspicuous in short sandy grassland on the lower slopes (photos 2-3).  This is an unusual sight in Assynt, since it is more usually found on sea cliffs and in salt marshes.

Mountain everlasting  Antennaria dioica was added to the plant list from rocky areas  above the path (photo 4).  Nearby were milkworts in two shades of blue; we took a closer look at these, since we have two species locally.  They were all common milkwort Polygala vulgaris, which has larger, more compact, heads of flowers (photo 5); despite its English name, it is the less frequent of the two.

More surprising was the discovery of a single example of the tiny fern moonwort Botrychium lunaria in the grassy hollow below the path at its northern end (photo 6), just before a gate onto more of the common grazings.  This is a new site for this rather fugitive species, which was later photographed here by David Haines (photo 7).

Butterflies seen nearby included several small heaths (photo 8), settling at an angle to sun themselves, like graylings and a common blue.

On 18th June, Michael and Valerie Pink, regular visitors to Assynt from Lanarkshire, found, at the moonwort site, a single frond of its relative adder’s-tongue Ophioglossum vulgatum, a new locality for this uncommon fern.  We later managed to locate four fronds in the long grass, all very small and only two with the ‘tongue-like’ spike that bears its sporangia (photo 9).

Early July

On 8th July, Gwen and Ian had a very productive reconnaissance for an Assynt Field Club meeting later in the month.  There is an old sand quarry between the house and the small burn (photo 10), south-facing and sparsely vegetated. Here we spotted the flattened heads of the tiny sea fern-grass Catapodium marinum (photo 11).  It is a coastal species, occurring in Assynt only at Stoer and Clachtoll, and elsewhere in the North West Highlands near Kinlochbervie.  It has not been noted in this quarry since 8th June 1990, and we later found it elsewhere on the site.

In open sandy areas were occasional pink-flowered rosettes of common stork’s-bill Erodium cicutarium (photo 12), some displaying the long, pointed, fruiting heads from which it gets its name.  It is a rare plant in Assynt, again confined to coastal grassland at Stoer and Clachtoll.  Also found, scattered through the grassland, was its slightly commoner relative dove’s-foot crane’s-bill Geranium molle (photo 13)

Wild carrot Daucus carota is another species almost entirely restricted to the coast in Assynt.  Many of those found on the Green are, unusually, virtually stalkless, so that their domed flowering heads sit at ground level in the short sward (photo 14).

A much commoner plant, yarrow Achillea millefolium, provided two features of interest.  One plant sported a head of pink flowers (photo 15), and Gwen photographed a colourful bug on a more usual head of white flowers (photo 16).  Stephen Moran identified it as the mirid Calocoris roseomaculatus.  This feeds as an adult on the flowers and unripe fruits of composites such as yarrow, but in the larval stage on bird’s-foot trefoil Lotus corniculatus, which is plentiful on the Green.  There are just two previous records of this bug from Assynt, both by Stephen, at Glencanisp Lodge (NC1122) and near Loch Assynt Lodge (NC1726), on 25th June 2017.

Whilst we were having lunch, just south of the gate, we were entertained by a slightly scruffy-looking juvenile wheatear (photo 17), perched on a fence post.

Later in July

On 18th July the Field Club held its first post-Covid field meeting at Stoer Green, with an attendance of 11, including two Leicestershire naturalists.  We took a look at the rich marsh and aquatic vegetation along the exit burn from Loch an Aigeil, and then walked along the top edge of the shingle, finding the tough bluish-green leaves of sand couch Elymus junciformis, a rare coastal species in Assynt.

The small burn traversing the Green was virtually dry (photo 18), but on damp mud at its mouth were examples of one of the monkeyflowers found in Assynt, Erythranthe guttata (photo 19), whose yellow petals bear small red dots. Monkeyflowers were originally introduced into cultivation from the American continent, but have escaped into the wild and since hybridised.  They are a colourful addition to burn-side vegetation throughout the North West, although only found near human habitation, where they presumably originated as garden throwouts.

Looking for Sea Fern-grass and Gentians

We then walked up the burn course to the old sand quarry to search for the diminutive sea fern-grass (photo 20).  Further up the slope we searched for autumn gentian Gentianella amarella, which was a challenge, since it was not yet in flower.  A path up through dense tussocks of marram grass Ammophila arenaria took us to the cliff-tops, along which we walked in single file to the grassy hollow housing the moonwort and adder’s-tongue.

On the way we did manage to find a few plants of field gentian Gentianella campestris in full flower (photo 21).  It flowers several weeks earlier than autumn gentian, but this year is not going to be a bumper season for either species, as was 2020.  Not far away, on a rocky outcrop above the path, were the showy white heads of sea mayweed Tripleurospermum maritimum (photo 22).  It is usually found nearer the shore-line, but here perhaps benefits from the reach of salt spray.

Lunch was taken at the end of the path (photo 23), where Gwen added another new species to the list for the Green, the tiny lesser clubmoss Selaginella selaginoides.   This indicates some base-richness in the adjacent Torridonian rocks.

On to Stac Fada

Since we had time to spare, we then continued along the cliff path, beyond the Green, to the unique rock outcrops at Stac Fada.  Leaving the path to skirt some Torridonian outcrops, Anna Wigmore spotted several rosettes of pyramidal bugle Ajuga pyramidalis, in a new locality.

In the opposite direction, a scramble down on to the shingle beach enabled us to show our visitors from land-locked Leicestershire two more maritime species on the low sea cliffs, sea spleenwort Asplenium marinum and rose-root Rhodiola rosea.

Approaching Stac Fada, we found two large stands of black bog-rush Schoenus nigricans just above the tide line (photo 24).  A very different habitat from inland base-rich mires usually housing this species; here the salts it requires are presumably supplied by salt spray.  Gwen photographed a colourful male common blue resting on the heads of bog-rush (photo 25)

We completed our excursion with a tea break on the edge of the Stac Fada Formation (photo 26).  When our attention was not being diverted by a small group of black guillemots bobbing about on the sea, we pondered the recent re-interpretation of the origins of these outcrops.

Stac Fada Formation

They are now thought to be ejectamenta from a colossal meteoric impact, dating back about 1177 million years, the crater from which may lie under The Minch, to the west.  It is estimated to be about 10km (6 miles) across and the impact to have resulted in ‘a blast with the force of 145,000 megatons’… ‘the shock wave [from which] would have created winds of 420 km per hour (260 mph) as far away as the site of the modern Aberdeen’.  All of which puts the effects of current global climate change into some perspective.

Whilst we were considering such enormities, two members of the party were favoured with a glimpse of an otter on the seaward edge of the Formation.  We would like to express our thanks to all present for their contributions to a most enjoyable field trip.

Ian Evans and Gwen Richards

For 2020’s survey, see Stoer Green: a Wealth of Flowers Revealed

 

 

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