A festival of ferns at Hareshaw Linn

An account of a fantastic day spent exploring fern identification at the glorious Hareshaw Linn.

Ferns have always scared me a little if I am honest. Sure, I can identify the easier ones but by large, I often ignore them on my travels in favour of less intimidating flowers. That said, I have been keen to improve my fern identification skills for a while now and on Friday set out with a friend to one of the most fern-rich sites in Northern England.

Hareshaw Linn is SSSI designated for its rare ferns and bryophytes. A scenic river gorge sporting ancient woodland and a rather beautiful waterfall, it is a site I had always wanted to visit but had not yet had the chance. Until now. Expectations already high, I am pleased to say I was not disappointed with fourteen fern species observed during our stay, including several new for me.

Starting out

Having given only an obligatory glance to the Male Fern (Dryopteris filix-mas) during our walk in, it wasn’t long until the first of the day’s more interesting ferns was discovered. The pictures below show Lady-fern (Athyrium filix-femina) found growing beside the path through the gorge. A lovely, feathery species with distinctive crescent-shaped sori, the best way to identify them is, of course, to turn them over.

Next up, a new species for me and further into the gorge, it was great to finally stumble across Lemon-scented Fern (Oreopteris limbosperma). Quite a nice one to identify, the best way to tell it apart from the pack is that the pinnae decrease in size as they go down the stem. It also gives off a pleasant citrus smell when crushed.

Hardly worthy of a mention but two more abundant ferns were added here too: Bracken (Pteridium aquilinum) and Broad Buckler-fern (Dryopteris dilatata).

Feeling brave, further into the walk, we decided to take a quick look at some of the other Dryopteris on site. I think the fern pictured below is a Golden-scaly Male Fern (Dryopteris affinis) having ruled out the Narrow-scaly Male Fern (Dryopteris cambrensis) based on the length of the lowest pair of pinnules. It also didn’t seem to fit Borrer’s Scaly Male Fern (Dryopteris borreri) either but I’d be happy to be corrected!

Moving on, new ferns soon started to come thick and fast. First came the first of many Hard Shield Ferns (Polystichum aculeatum) spotted during the trip and secondly, lots of Hard Fern (Blechnum spicant). Feeling empowered by the earlier male fern, we also chose to take a closer look at the Polypodys growing alongside the river. With pointed tips and fronds which gradually taper towards the top and bottom, I think these were Intermediate Polypody (Polypodium interjectum).

Nine species and counting

Drawing closer to the waterfall, a quick detour from the track revealed another new species for the day: Oak Fern (Gymnocarpium dryopteris). With fronds split roughly into three triangles, this is another nice one to identify and another new species for me.

Reaching the waterfall, it was difficult not to be taken aback by the visible storm damage. The plunge pool beneath the waterfall was littered with the corpses of felled trees, likely brought down during Storm Arwen. I wouldn’t have liked to be here that night…

Back to the ferns, and Hareshaw Linn is the only North East site for the rare Lobed Maidenhair Spleenwort (Asplenium trichomanes subsp. pachyrachis). A nationally scarce subspecies of Maidenhair Spleenwort, the difference between them comes from the lobed, crinkley-looking pinnae. We saw many plants during our stay, all concentrated around the waterfall where they grow within cracks in the bedrock.

Here too, the steep cliffs of the gorge and fallen rocks beneath them held a number of other ferns. Some, like Hart’s-tongue (Asplenium scolopendrium) were somewhat common, though others much less so. Green Spleenwort (Asplenium viride) is a rare species locally and took some finding among the much more numerous Maidenhair Spleenwort.

Slightly more conspicuous, Brittle Bladder-fern (Cystopteris fragilis) could be seen in abundance too. The latter species concluded the day’s tally at a very respectable 14 fern species.

Other wildlife

While ferns were the purpose of the day’s trip, plenty of other wildlife was seen at Hareshaw Linn. The plantlife was particularly interesting with sightings of several species I see infrequently in the North East. Among these, Wood Horsetail (Equisetum sylvaticum), Wood Melick (Melica uniflora) and Marsh Hawk’s-beard (Crepis paludosa). Of course, several Giant Bellflowers (Campanula latifolia) were also a highlight.

The combination of beaming sun and rain showers did not prove overly encouraging to insects. However, we did see a few goodies including new hoverflies for me in Epistrophe grossulariae and Leucozona laternaria. Returning to the car park, the bee below was also spotted foraging on a Solidago sp. Thanks to Chris, this was revealed to be Grey-banded Mining Bee (Andrena denticulata), an incredibly rare species in our region.

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