A visit to the ‘high limestone’ at Inchnadamph

August 8th 2020

A visit to the ‘high limestone’ at Inchnadamph

Some parts of Assynt are botanical ‘hot-spots’.  One such is the ‘high limestone’ behind Inchnadamph (NC2718), properly Cnoc Eilid Mhathain (’rounded hill where hinds abound’). This ridge of Cambrian limestones lies immediately to the north of Beinn nan Cnaimhseag and rises to 470m.  To quote the Flora of Assynt (2002, p.38), it is ‘renowned for its Dryas-dominated grassland, crevice and ledge communities and has a range of less common species, found sparingly, if at all lower down’, including ‘Arenaria norvegica [arctic sandwort], Minuartia sedoides [mossy cyphel], Potentilla crantzii [alpine cinquefoil], Saussurea alpina [alpine saw-wort] and Silene acaulis [moss campion]’.

The forecast for 23rd June 2020 looked good, warm but breezy, and it needed to be since the round trip to the summit of the hill is over 10km, with 390m of height to climb.  We left the car at the Old Post Office and set out at 1000 hrs.; coffee was taken near the Traligill Caves (Cnoc nan Uamh) and we then struck across hummocky ground to the northern shore of Loch Mhaolach-coire (also known as the Gillaroo Loch, once famous for unusual brown trout) and up to the foot of the hill (photo 1).  We had lunch by a small burn about 200m short of the lower edge of the limestone and reached it at about 1330 hrs.  Here we split up, Gwen and Jess to climb the remaining 150m (500ft) to botanise the summit (photo 2), while Ian, who had run out of steam, investigated the skirts of the hill.

Higher ground

Gwen returned two hours later, having located and photographed most of the rarities. Included were arctic sandwort, alpine saw-wort and moss campion (photos 3-6), as well as many commoner limestone plants, such as green spleenwort Asplenium viride in crevices (photo 7) and a compact form of limestone bedstraw Galium sterneri (photo 8).

Gwen’s prize find however, near the summit of the hill, was the local rarity heath dog-violet Viola canina.  ‘Heath’ is a misnomer in Assynt, since it has only been recorded twice before, both times on limestone.  It is a different shade of blue from the ubiquitous common dog-violet V. riviniana, and has a shorter, rounder, pale yellow spur and rather more triangular leaves (photo 9).  She also heard golden plover at the northern end of the ridge and had splendid views across to Conival (photo 10) and back down Gleann Dubh to Loch Assynt and Quinag (photo 2).

Meanwhile, Ian had logged over 60 species along the edge of the limestone and in flushes running off it (photo 11). These included typical limestone plants such as mountain avens Dryas octapetala (still in flower, photo 12)) and frog orchid Coeloglossum viride and, on adjacent heathery ground, two characteristic plants of the higher slopes of our hills, dwarf cornel Cornus suecica (photo 13) and cloudberry Rubus chamemorus (photo 14).

His best find, in a damp grassy runnel, was a ‘new’ site for the locally rare shade horsetail Equisetum pratense (photo 15).  It bears a superficial resemblance to the much commoner wood horsetail E. sylvaticum, but the umbrella-like whorls of branches are not again branched.  He also disturbed an orange and black frog (photo 16), one of a number seen; they are often more colourful on the hills.

Return from the hill

After a tea break and comparing finds, we set off back to the shore of Loch Mhaolach-coire, passing an active but hitherto unrecorded water vole colony along a small burn.  Having failed to find the fishermen’s path, for the second time, we followed a dry valley with sink-holes from the northern end of the loch, on the edge of which Gwen photographed a very dark caddisfly (photo 17).  She later identified it as the Welshman’s Button Sericostoma personatum.  This is a widespread species, whose larvae make characteristic cases of fine sand grains.  Such cases turned up several times in her Quinag Lochs Project (2010) and the presence of this species is indicative of very high water quality.

Other insects noted during the day included Common Blue, Large Heath, Meadow Brown and Small Heath butterflies, late larvae of the Northern Eggar moth and adult Chimney Sweeper moths; we also saw one common lizard.   We were back on the path at Cnoc nan Uamh for a second tea break at 1700 hrs, and finally reached the car after more than eight hours on the hill, fairly weary, but with some sense of accomplishment.

Alpine cinquefoil Potentilla crantzii

This was the one rarity that Gwen was unable to find.  It is a scarce species of montane basic grasslands and rocky places in Scotland, and was first noted on Cnoc Eilid Mhathain as ‘occasional colonies’ by the Cambridge botanists John Raven and Max Walters on 29th August 1953.  It was recorded again a few times in the 1960s and 1980s and last seen by Pat and Ian, on just one rocky ledge, at about NC277183 (pre-g.p.s.), on 31st July 1994.

One other discovery, by Pat, Ian and Gordon Rothero, was on the very highest limestone outcrop in Assynt, at over 500m, in Bealach Traligill (NC302191) on 30th August 1998. That site is even more remote, and has not been botanised since, so far as we know.  By sheer coincidence, Gordon found this species at about 900m on Ben Dorain (NN3238) in the Grampian Mountains north of Tyndrum, on 10th July 2020.  He describes his photograph (photo 18) as ‘not a great shot, since I was teetering and there was a drop below me’, but it is included to help anyone who aspires to re-find alpine cinquefoil in Assynt. Slightly-larger five-petalled flowers and palmate basal leaves distinguish it from the ubiquitous tormentil Potentilla erecta.

Please let us know if you find it at either site.

 

Ian M. Evans and Gwen Richards

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