The Urban Ferns of Newcastle and North Tyneside

While recording for the Urban Flora, I’ve now encountered a total of 23 fern species growing in a wild or naturalised state within the conurbation. An additional three species have been submitted by fellow recorders, bringing the total to a healthy 26. This is quite an impressive number given the area covered, though it still represents a relatively small 2.3% of the total plant species recorded from the area.

Nonetheless, urban ferns are an interesting bunch. In the style of my previous posts [here] and [here], I thought I’d explore them properly on this blog — partly for reference, and partly in the hope that someone, somewhere, finds these rambles either useful or at least somewhat interesting.

Before I go any further, however, a very big thank you to Chris Barlow and David Jarema for making their photography available for projects such as this. It is most appreciated.

Common Ferns

The Big Five

The “big five” urban ferns represent the most common and widespread species within the conurbation. All are fairly familiar and either thrive in a wide variety of habitats or are associated with environments so ubiquitous that they’ve become an almost daily sight.

Chief among them is the Male Fern Dryopteris filix-mas, which has so far been recorded in 135 squares—an impressive 71% of those surveyed. It’s truly a fern that gets everywhere: from woodlands and hedgerows to urban walls, gutters, gardens, and even pavements close to overflowing drainpipes. While I doubt it will turn out to be truly ubiquitous across every square, it’s about as close as a fern can reasonably get.

Not far behind in the numbers game is Hart’s-tongue Asplenium scolopendrium, an evergreen fern of moist, shaded woodlands that is also frequently encountered on mortared walls and masonry. Recorded from 102 squares (53%), it’s certainly abundant.

Two other “wall ferns” are also doing well: Wall-rue Asplenium ruta-muraria, noted in 84 squares (44%), and Maidenhair Spleenwort Asplenium trichomanes, in 70 squares (36%). While marginally less widespread, both can be prolific where they occur – typically in older, more unkempt terraced neighbourhoods, where less rigorous weeding allows them to thrive. In contrast, they can be surprisingly scarce in modern developments or more affluent areas where tidiness tends to take priority.

The final fern worthy of inclusion in this section is Broad Buckler-fern Dryopteris dilatata. Typically a species of somewhat acidic, damp soils, it’s most often encountered in woodland settings. However, it has proven far more catholic in its habitat preferences than many other woodland ferns, turning up readily in newer woodlands, plantations, hedgerows, rail embankments, and even grassy habitats on occasion. So far, it has been recorded in 48 (25%) survey squares.

Localised Ferns

The next group of ferns are altogether more particular in their habitat preferences and occur much more sparingly across the conurbation — though not quite so sparsely as to be considered rare. With the exception of one notable species, all are best described as woodland ferns within Newcastle and North Tyneside. We’ll look at these first.

Hard Shield-fern Polystichum aculeatum and Soft Shield-fern Polystichum setiferum make for an interesting duo. The former is native to the area, typically inhabiting damp, shaded stream-sides and rocky ledges within woodland. The latter, meanwhile, is a more recent arrival, introduced occasionally but now subject to natural colonisation as well. Intriguingly, the two species are neck-and-neck in terms of occurrence, each recorded from 10 survey squares (5%). Both remain closely tied to the relic semi-natural woodland of Newcastle’s denes, though Soft Shield-fern has begun to spread a little more widely.

Another interesting pair are the Scaly Male-ferns. Within the conurbation, we seem to host two fairly frequent species and one rarer one (which I’ll cover later). Among the more commonly encountered are Borrer’s Male-fern Dryopteris borreri and Golden-scaly Male-fern Dryopteris affinis.

Of the two, D. borreri is notably more abundant, recorded in 26 survey squares 13.7%. While it tends to favour older woodland habitats, it also turns up elsewhere including newer plantations. D. affinis, on the other hand, is much more selective, preferring damp locations in older woodlands, and has been recorded in just 7 squares 3.7%. In fact, the only places I’ve found it in any real abundance are Jesmond and Wallbottle Denes, now that I think about it.

The conurbation’s wooded denes are also just about the only places where you’re likely to encounter Hard Fern Blechnum spicant these days. Recorded in 8 survey squares 4.2%, it is largely restricted to Sugley, Walbottle, Jesmond, and Denton Denes – with the only notable outlier being a small population at Gosforth Nature Reserve where the acid soils suit it well.

Two more uncommon species associated with the conurbation’s woodlands – albeit with a bit more flexibility – are Lady-fern Athyrium filix-femina and Bracken Pteridium aquilinum.

Lady-fern, recorded from 21 squares (11.1%), remains fairly localised, with the best populations once again found within the area’s wooded denes. However, it will readily colonise other damp, shaded spots such as ditches, hedgebanks, and more recent plantations.

Bracken, by contrast, is quite the opposite. It favours somewhat acidic soils in the drier, upper reaches of older woodlands, where it can be particularly abundant. Still, it’s far from confined to such settings and occurs more broadly across the conurbation as a colonist of all sorts of habitats, especially rail sidings and grassy banks. In total, Bracken has been observed in 29 squares (24%), though it is by no means “common”.

The final species worthy of mention at this stage is, rather refreshingly, not a fern of woodlands but instead a calcicole, favouring mortared walls in urban areas. Black Spleenwort Asplenium adiantum-nigrum has been recorded from 28 squares (14.7%) so far. While one of the less common wall ferns overall, it can be surprisingly plentiful in certain neighbourhoods, particularly around Walker, Heaton, and Wallsend. It also occurs sporadically in squares around Newcastle City Centre, including in spots where even more typical ferns like Wall-rue are absent.

Rare and Scarce Ferns

And so we come to the conurbation’s rare ferns – the ones that truly generate excitement when you stumble across them. There’s a surprising number of these, though they all tend to fall into two distinct categories: rare natives or exotic introductions. We’ll start by looking at the native species first…

Scarce Native Species

Kicking off our collection of rare woodland ferns is a duo found exclusively at Gosforth Nature Reserve —suggesting a preference for mildly acidic conditions.

Narrow Buckler-fern Dryopteris carthusiana has long been a rarity in the conurbation, with no local records since George Swan encountered it in the Gosforth Park back in the 1970s. That changed recently when local botanist, John Durkin, rediscovered it in wet woodland and relic acid grassland at the reserve. Found in just 1 square (0.5%), it is by all accounts a true local rarity. The same goes for its hybrid with Broad Buckler-fern, Dryopteris x deweveri, also noted from a single square (0.5%) during surveys by the same recorder.

Speaking of hybrids, Polystichum × bicknellii — the cross between Hard Shield-fern and Soft Shield-fern —has so far only been recorded from Jesmond Dene, where both parent species occur. Meanwhile, Gosforth Nature Reserve has produced two further exciting finds: Narrow Male-fern Dryopteris cambrensis and Lemon-scented Fern Oreopteris limbosperma, each recorded from just one square (0.5%). Both are, for now, exceptionally scarce within the conurbation.

Rustyback Asplenium ceterach has long been a rare fern on Tyneside. For years, it was known only from an exterior garden wall in North Shields where happily, it still persists today. Encouragingly, it was also recorded last year on an exterior wall in Brunswick, where it was growing in mortar alongside a mix of more familiar species. So far, Rustyback has been observed in just 2 squares (1.1%).

And since we’re on the subject of walls, now seems a fitting moment to turn our attention to the urban Polypodium species. Both Polypody Polypodium vulgare and Intermediate Polypody Polypodium interjectum are rare within the conurbation — though they may well be under-recorded.

P. vulgare has proven the more widespread of the two, typically occurring as a thinly distributed epiphyte of older woodlands, with records from Jesmond, Sugley, and Denton Denes. It also occasionally turns up on old walls, though here it remains quite scarce. To date, it has been recorded from 9 squares (4.7%). In contrast, P. interjectum is more characteristic of mortared walls and has been noted as a scattered colonist in 3 squares (1.6%).

A final rare native worthy of mention is the unusual Adder’s-tongue Ophioglossum vulgatum, a species typically found in higher-quality, neutral to acidic grasslands. Within the conurbation, it appears to be in decline – likely as aa consequence of poor grassland management in many areas. So far, it has been observed from just two well-known sites: a verge along Salter’s Lane and, in greater numbers, from grassland near Havannah Nature Reserve. It remains restricted to 2 squares (1.1%).

Some Exotic Ferns

As I’ve touched on in previous posts, Jesmond Dene is home to its fair share of weird and wonderful exotic plants, including several ferns. Most of these have been encountered near the remnants of a derelict Victorian fernery, and it’s hard to say whether they’ve persisted here for decades or are the result of more recent introductions. Either way, three exotic species now appear to be growing wild in the Dene: Japanese Shield-fern Polystichum polyblepharum, Japanese Buckler-fern Dryopteris erythrosora, and Western Sword-fern Polystichum munitum, each recorded from a single square (0.5%).

A fourth species, House Holly-fern Cyrtomium falcatum is not found in the dene but instead, has been noted from the base of a sunny garden wall in Gosforth – clearly having spread from planted stock nearby.

And really, who doesn’t enjoy a touch of the exotic while botanising the big city?

And there we have it, a not-so-concise tour of the urban ferns recorded as part of the project so far. There’s a surprising number out there waiting to be discovered. With the conurbation’s woodlands now fairly thoroughly surveyed, I suspect the distributions of many woodland species will remain relatively stable by the time the project wraps up. That said, we may well see an uptick in species colonising walls and masonry, particularly as urban habitats are surveyed in more depth.

I can’t imagine there are too many more species left to uncover but given the exotics mentioned above, you never really know what might be lurking just around the corner, do you? Good job there are some handy resources out there…