Category Archives: Bristol

Fly Orchids in the Avon Gorge


Fly Orchid (Ophrys insectifera) is in flower currently in the Avon Gorge. To see the most accessible plants, head north on the towpath on the west side of the gorge, to an area of rock falls about half a mile north of the Suspension Bridge. I counted 10 plants in flower today by the fence at the bottom of the rocky slopes (see map & photo below). Here they grow in the open, in limestone grassland, but at other sites Fly Orchids occur in woodland.

Fly Orchid is a scarce plant around Bristol. The Avon Gorge is the only site in close proximity to the city: the location I visited on the North Somerset side is the most well-known, although Fly Orchid has also been found occasionally on the Bristol side. Elsewhere in the region, there is a cluster of sites in the Avon valley southeast of Bath, including Browns Folly and Avoncliff. There are several other sites farther south and east of here into Wiltshire and east Somerset, including Cleaves Wood near Wellow, Morgans Hill near Devizes, and a grassy bank on the north side of the A303 near Wincanton. Elsewhere in Somerset, Fly Orchid is only found on cliffs near Blue Anchor. Its stronghold is in the Cotswolds, with around 10 sites in the Stroud area and others southeast of Cheltenham. Although it formerly occurred in the Wye Valley, it is now extinct there.


Pollination is carried out by male digger wasps of the genus Argogorytes, which are attracted to the flowers by a pheromone; they mistake the flower for a female digger wasp and attempt to mate with it. In doing so, the orchid’s pollen sacs attach to the wasp, and are then transported to the next orchid the wasp visits. The Avon Gorge Fly Orchids are of particular note, as in the past, this process went a little awry and hybridisation occurred with Bee Orchid (Ophrys apifera): when these hybrids were first discovered here, in 1968, they were new to science. Hybrids are not known from the Avon Gorge currently, but they are present at the Wincanton site. Hybridisation has also occurred in Kent with Early Spider Orchid (Ophrys sphegodes).

A Siberian Chiffchaff on a Bristol dung-heap

Common Chiffchaff (Phylloscopus collybita) is a leaf-warbler familiar to birdwatchers in Britain, as a common summer visitor, and in much of the country as a winter visitor in small numbers. Its eastern cousin tristis, Siberian Chiffchaff, also regularly winters in Britain, and there’s currently one in Boiling Wells Lane, at the north end of St Werburghs. The stream from which the lane gets its name, and a nearby dung-heap, are attracting plenty of insects, keeping our Siberian visitor loyal to a very small area. Here’s a photo:


A lot of confusion surrounds the status of Siberian Chiffchaff in Britain, more of which below, but they are pretty distinctive birds, especially if you have the opportunity to compare one with Common Chiffchaffs, of which there are up to four at Boiling Wells currently. Siberians are paler birds, particularly on their underparts, which are whitish, lacking the yellowish-buff colours present on Common Chiffchaff. The upperparts are pale grey-brown, usually without the green tones of Common Chiffchaff, although the flight-feathers and the tail can be finely edged with green. Usually there is a warm buff colour on the cheeks and breast-sides, and there can often be a narrow pale wingbar. The bill and legs are black and so are conspicuously contrasting compared with the pale plumage. Finally, both songs and calls are different: the St Werburghs bird gives the typical call of Siberian Chiffchaff, a soft single-syllabled ‘peep’, neither rising nor falling, different from the rising, slightly disyllabic ‘hueet’ call of Common Chiffchaff. If it’s a male, it may start singing later in the winter: instead of the repetitive ‘chiff … chaff’ song, Siberian’s song has a more varied structure to it.

The confusion I mentioned above has a long history. First, in the 1950s and 1960s, several SIberian Chiffchaffs were mistaken for Greenish Warblers (Phylloscopus trochiloides), something that seems hard to believe today, with improved knowledge and better optical equipment. More recently, there has been a wide-ranging debate about the identity of non-calling birds, especially those which differ from the typical appearance described above. Midlands birder Alan Dean has highlighted several such birds which he terms “grey-and-white chiffchaffs”, and believes that these are not Siberian Chiffchaffs, but either eastern Common Chiffchaffs or the result of hybridisation where the two meet.  This has caused many birders to doubt the identity of many of the birds they’ve seen.

Thankfully, things may not be as bad as Alan suggests. Birders based in Poole, Dorset have been studying their wintering chiffchaffs, and concluded that at least some of the birds which do not conform to the typical appearance still call and sing like Siberians. More recently, ornithologists in the Netherlands looked at the DNA of birds trapped for ringing, and discovered that not only did birds identified confidently as Siberian Chiffchaffs have the right DNA, so did a large number of other birds, all of which had been tentatively identified by their ringers as Scandinavian Common Chiffchaffs (Scandinavia is one area the “grey-and-white” birds have been thought to come from). Interestingly, none of the birds in this study had DNA which matched birds from Scandinavia, even though the Dutch ringers had specifically been looking out for them, and all of the normal-looking Common Chiffchaffs trapped were just that.

There has also been a study in western Russia, looking at if and how frequently the two hybridise. The answer? Yes, just like us humans, some chiffchaffs are confused about chiffchaffs and hybridisation does occur. However, it only occurs in a narrow zone some tens of miles wide where the two populations overlap. West of this for several thousands of miles are normal Common Chiffchaffs, while normal Siberian Chiffchaffs are found east almost all the way to the Pacific Ocean. Numerically, hybrids are so rare that they can’t really be the cause of Alan Dean’s puzzle.

There are dozens of other Phylloscopus warblers in Europe and Asia, and many of these are difficult to tell apart visually, but have distinctive calls and/or songs – indeed, several new species have been described based on this in the last twenty years or so. Siberian and Common Chiffchaffs seem to be another one of these species-pairs. Historically, Siberian Chiffchaff has been considered a geographical race of Common Chiffchaff, however given what we now know this is not really appropriate. Because of the narrow hybridisation zone, they are probably best considered “semispecies” (biological jargon which means that, although not everything’s completely sorted out in the overlap zone, evolution has basically done its job and the two are on separate future trajectories).

I did a little bit of birding PR today with the owners of the dung-heap: they had wondered if all the people with cameras who had been visiting this week were from Bristol City Council and were eyeing up their land for house building. I showed the bird to them and explained why it was attracting interest, and I think they’re now happy that their visitors are all just perfectly normal people who just happen to like looking at birds on dung-heaps. They regularly turn the dung, exposing more of the chiffchaff’s food, so hopefully it will hang around for quite a while.

Here’s a map showing the area the bird frequents:

Lanceolate Spleenwort in Oldbury Court woods

The fern in the photo below is Lanceolate Spleenwort (Asplenium obovatum), a scarce species which is mainly found in coastal locations in southwest England and Wales, but which has a small population in the woods on the Oldbury Court estate (a location sometimes also referred to as “Glen Frome”), where it was first found in 1835.


There are several features which enable Lanceolate Spleenwort to be told apart from its more common relative Black Spleenwort (Asplenium adiantum-nigrum). To make this easier to follow, I need to introduce a few bits of fern terminology. The stipe of a fern is the main stalk of a fern frond. In most fern species, the frond is divided up: the main segments are called pinnae, and the lobes on each pinna are called pinnules.

Lanceolate Spleenwort has an elongated oval or oblong frond, with the pinnae nearest the base usually shorter than the ones further along, and these are often bent back towards the base of the plant (you can see this on some of the fronds in the photo if you look carefully). By contrast, in Black Spleenwort, these lowest pinnae are usually the longest, giving the frond a triangular shape. On Black Spleenwort the stipe is also usually much longer than on Lanceolate Spleenwort. I’ve included a photo of Black Spleenwort below, taken at a nearby location, and both of these features are obvious. There are other differences visible when you examine the fern close-up: the sori (spore-bearing bodies) on the underside of the leaf of Lanceolate Spleenwort are found only around the edges of the pinnules, whereas in Black Spleenwort they spread in a fan shape from the vein in the centre of the pinnule. Black Spleenwort gets its name from its solidly black stipe, whereas Lanceolate Spleenwort’s stipe is a green colour above, with a dark brown stripe below,


Lanceolate Spleenwort grows in sheltered fissures and crevices on acidic rocks, although in the warmer far southwest, it is also found on hedgebanks in lanes. The largest British populations are on sea cliffs in Devon, Cornwall and northwest Wales. The Oldbury Court site is the easternmost extant site in Britain for this species, and is isolated from other populations of Lanceolate Spleenwort by many tens of miles. In southwest England it is not found again until Exmoor, and in south Wales, not until the Gower peninsula, although there are old records from Beachley near Chepstow. Its northernmost locations, in Cumbria and southwest Scotland, are also very isolated. Globally its range extends south through France, Spain and Portugal to the Canary Islands, Madeira and the Azores, a distribution-type that is shared by a number of other fern species. Black Spleenwort is nowhere near as fussy, liking all rock types (loads of it grows on the limestone in the Avon Gorge, for example); I have even found it on walls in the city centre, near the Bristol Royal Infirmary and Old Market.

Here is the location of the plant I photographed (and a photo of the outcrop on which it was growing). If you want to visit it yourself, take care as it is on a steep muddy slope, high above the river. The best approach is to head up the zigzag footpath from the weir, and then take a right turn when you reach some railings. However, there are lots of similar-looking outcrops in the valley, from Eastville Park northeast to Winterbourne and it wouldn’t surprise me if some of these had their own mini-populations of Lanceolate Spleenwort too.


Autumn Ladies-tresses on Bristol Downs

There are a few flowering plants that wait till the end of the summer before flowering, and Autumn Ladies-tresses (Spiranthes spiralis) is one of them, never flowering before August and continuing well into September. This is probably the least conspicuous of the orchids which are found in the Bristol area, typically only reaching about ten centimetres tall. The photos below show the way in which the tiny flowers spiral around the stem, a feature reflected in its scientific name.


I visited the colony on Bristol Downs today, and counted at least 87 plants – although among these were many which weren’t in full flower yet, which I only noticed when I was on my knees next to plants which were in flower, so as I will have no doubt missed other similar individuals, I’m confident the total population here is well into three figures.

Here’s the location: right next to the circular road which runs around the Downs.

Autumn Ladies-tresses is a plant of very nutrient-poor limestone and chalk grassland. In most locations, sheep do the work of keeping the habitat conditions right; on the Downs, in the absence of sheep, the grassland has to be managed by mowing and raking off the cuttings. On the side of the colony closest to the road, the soil has been badly eroded by runners; fences have been erected to encourage people off of this part of the site, in the hope that it will regenerate.

The Downs as a whole are a bit of a curate’s egg botanically, even if you discount the areas which are formally set aside for sports. Although it is certainly the largest area of limestone grassland around Bristol until you reach the Mendips and Cotswolds, that doesn’t necessarily mean it’s good-quality limestone grassland throughout. Some areas are good – I found a few Harebells (Campanula rotundifolia) growing in another spot today, for example – and the stone workings on the southeast side have some botanical interest, as does the area around the observatory. However, other parts are quite species-poor. With the right management to reduce the nutrient levels, though, the Downs could certainly become a lot richer, and complement their neighbour the Avon Gorge.

Two scarce riverbank plants

Earlier this month, I took a walk along the River Avon from Conham to Hanham. to check out some of the scarce plants which occur locally in riverbank habitats. The highlight was this Greater Dodder (Cuscuta europaea), a parasite of the Common Nettle (Urtica dioica): the upright green stems are those of the nettle, and the red stems twining around them belong to the dodder.

This is a nationally scarce plant, found in only a handful of areas in southern and central  England. Locally, it occurs in two areas. It is found along the River Avon from Bristol upstream to Bath, and again to the east of Bath into western parts of Wiltshire; its other stronghold is along the River Severn (mainly around Gloucester but with an outlying site near Frampton-on-Severn).


The closely-related Common Dodder (Cuscuta epithymum) also occurs in our area, and is also a scarce plant, despite its name. It is found in heathland and dry grassland and parasitises among other things, species of gorse, heather and thyme. It has smaller flowers, although to be certain of the identity of a dodder specimen, a flower has to be dissected under a microscope, to look at tiny features such as the shape of the minute scales at the base of the inner surface of the flower and the relative length of the sex organs.

Here’s the area where I found the plant photographed above:

Also present in good numbers throughout this section of the Avon was Small Teasel (Dipsacus pilosus), the scarce relative of the ubiquitous Common Teasel (Dipsacus fullonum). In and around Bristol, it is found on the River Avon between Bristol to Bath, on the River Frome in northeast Bristol, on the River Chew, and scattered other localities, often in or on the edge of woodland.

Small Teasel 1 Small Teasel 2

Roesel’s Bush-cricket

It’s the time of year when orthopterans are out in force just about anywhere with any decent vegetation. There are four families represented in Britain: grasshoppers are common and familiar; the larger bush-crickets (which many people just refer to as “crickets”) are less conspicuous but still common; then there are the groundhoppers, which take a bit of searching for, and the true crickets, which are just downright rare. This diversity is the reason for going ever-so-slightly jargony with that first sentence: there isn’t really a single good shorthand name, the best compromise probably being “Grasshopper and crickets”.

They are quite an easy group to get to grips with, as there are only about 30 species in Britain, and the species featured in Vic Savery’s photos below is an easy one to identify: the long antennae and chunky body are characteristic of a bush-cricket, and the pale crescent around the edge of the side-panels of the thorax are a dead giveaway for Roesel’s Bush-cricket (Metrioptera roeselii).

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Roesel’s Bush-cricket, 12 August 2013, Avonmouth, Bristol, Vic Savery (

When the last national Orthoptera atlas was published back in 1997, Roesel’s Bush-cricket was largely confined to the Home Counties, with isolated outlying coastal populations in a few other areas. However, like a number of other species of bush-cricket, its populations have expanded since then, and it now occurs around Bristol. It is well-established in Wiltshire and Gloucestershire and has also spread into Gwent in the last decade. Robert Cropper’s 2011 book “The Orthoptera and allied insects of Somerset” documents surprisingly few Somerset sites: a strong population around Bridgwater possibly marks the southwestern edge of the current British range, although the range expansion is no doubt ongoing, so I’m sure that the species will reach Devon soon if it hasn’t already.

The song of Roesel’s Bush-cricket is a high-pitched buzzing, pitched at around 22 kHz. If like me, your hearing has deteriorated to the point where you can’t hear sounds which are that high-pitched, you’ll need to use an electronic detector to track one down. Vic tells me there were three or four singing at his site, on Kingweston Lane near Avonmouth. In all likelihood there are other sites elsewhere in the city too.

Green-flowered Helleborines

Ashton Court, a walled estate just to the west of Bristol is famous for hosting the Bristol International Balloon Fiesta, but it has a botanical claim to fame too: the only accessible Green-flowered Helleborines (Epipactis phyllanthes) in the Bristol area grow here, in a dark wooded part of the estate called Clarken Combe, just a short hop over the wall from a layby on the B3128. I paid the site a very quick visit last weekend and was surprised to find many more plants than I’ve seen here previously, although all were still in bud. This weekend, however, several were flowering: mostly each plant had just a single stem, but one plant had a cluster of nine: here is a photo, and a close-up of some of the individual flowers.


These plants have an interesting history. Originally found in 1985, they were thought to be Narrow-lipped Helleborines (Epipactis leptochila), a scarce species of limestone beechwoods. They were listed as this species in the Flora of the Bristol Region, published in 2000, and this identification remained unchallenged until fairly recently. I paid the site a visit in late summer 2011, not really knowing any more than to look in the woodlands at Clarken Combe, I narrowed my search by looking under beech trees, and eventually found three helleborine plants, but they were past flowering, so I visited again in 2012 with Martyn Hall, who took some photos. Still none the wiser as to the plants’ true identity, I posted these to the orchid thread at Birdforum. Midlands-based orchid expert Sean Cole posted a reply, asking whether I was sure the plants were Narrow-lipped Helleborines, as they looked to him more like Green-flowered. That afternoon, Richard Mielcarek and I went back to Clarken Combe, gave the plants a very close look, and confirmed that, just as Sean thought, they were Green-flowered Helleborines.

Part of the reason for the confusion is that back in the 1980s, knowledge about the variability of the Epipactis helleborines, and which identification features are most reliable, was still developing: nevertheless, the plants had been visited by many knowledgeable botanists since, and so it’s surprising that it took so long for them to be re-identified.

Green-flowered Helleborine occurs in several varieties (forms of characteristic appearance caused by small genetic differences). The Clarken Combe flowers open quite widely, seem to have a clear distinction between the ‘cup’ (hypochile) and the ‘lip’ (epichile) and in some, the lip is bent back under the cup, whereas in others it is not, and then appears quite long and pointy. As I understand it, this points to them being of the variety known as ‘vectensis’, but I’d be interested in views from others with more knowledge of this subject. The pointy lower lip and the fact that the flowers open widely may be one of the reasons why the plants were originally thought to be Narrow-lipped Helleborines. However, the hypochile of Narrow-lipped Helleborine is filled with a sticky dark purplish liquid, not present in the Ashton Court plants, and the lip of Narrow-lipped is even longer and thinner. There are several other features visible with a hand-lens, which Richard and I checked last year to satisfy ourselves that our re-identification was correct.

In a local context, Green-flowered is only marginally less rare than Narrow-lipped. Narrow-lipped’s nearest population is in the woodlands at the top of Cheddar Gorge; Green-flowered occurred in the past on the towpath below Leigh Woods, but has not been seen here for many years, and only occurs at one other site, a private garden near Stowey. Further north, on the Cotswolds, both species have strong populations, and Green-flowered also occurs at several sites in Wiltshire. Nationally, Narrow-lipped is the scarcer of the two, and its populations are in decline, whereas Green-flowered is if anything on the increase.

Here is a map showing the location of the plants. If you visit, please take great care where you put your feet, as some of the plants are quite small. There are differing views among botanists about the levels of secrecy that should surround locations of scarce plants, and in particular orchids. One orchid site on the edge of Bristol suffered from theft of a very rare species this year, so concerns are very valid. Fortunately, I don’t have to make the decision over the Ashton Court plants, as Bristol City Council have publicised them for many years as one of the features of the site (albeit unwittingly as the wrong species).

Lamplighters Marsh

Last week, I visited one of my favourite Bristol plant sites, Lamplighters Marsh. This is the strip of land between the Avonmouth railway line and the River Avon, from the M5 Avon bridge southeast to the former Lamplighters pub. It’s got a mix of habitats: lots of scrub and tall herb, one of Bristol’s few reedbeds, and areas of sparse vegetation (and the tidal Avon, a interesting site in its own right, is right next door). Here are a few photos of the site:

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Among the star plants here are a large population of Viper’s Bugloss (Echium vulgare) and a small population of Moth Mullein (Verbascum blattaria), both scarce plants in the Bristol area. Viper’s Bugloss occurs in a variety of habitat types in Britain: chalk and limestone grassland, at the coast in sand dunes, on shingle or cliffs, and in disturbed open ground such as that found in disused quarries or railway lines. Although Lamplighters Marsh could be described as coastal, the habitat here is more like the last of these, and in the Bristol area, it is not really a coastal plant, although in some parts of Britain it is exactly that. My visit was on a sunny evening and many bumblebees were visiting the plants.


Moth Mullein is an introduced plant. It is distinctive among the mulleins in having large flowers, and not being densely hairy or downy like many mullein species. It occurs in both white-flowered and yellow-flowered forms.  It has been recorded at several other sites in Bristol, but is very scarce away from the city.


Rodway Hill

Rodway Hill is an open space on the edge of Mangotsfield. As well as being a valuable resource for local people, it has an interesting plant community: it is part of the suite of acid grasslands which can be found dotted around the eastern edge of Bristol. Our best local grasslands are usually either calcareous (limestone) grassland or neutral hay-meadows; acid grasslands are rarer. All three types have distinct plant communities. In upland areas elsewhere in Britain, acid grassland is common, but because it is so scarce in the Bristol area, acid grassland species common elsewhere are scarce, and some of the scarcer plant species associated with this habitat are genuine local rarities. Here’s a photo of the site:


and here’s a map:

One of the more obvious herb species on Rodway Hill and in other local acid grasslands is Heath Bedstraw (Galium saxatile). The two bedstraws which are more commonly found in the countryside, Cleavers or “Goosegrass” (Galium aparine) and Hedge Bedstraw (Galium album), are often found sprawled among taller vegetation, but Heath Bedstraw is invariably a compact low-growing plant, with flowers packed into clusters, and this gives it quite a distinctive appearance. There are several characters you can look for with a hand-lens to confirm the appearance, including the smooth stems, the small leaves with a little point projecting from the rounded tip (this leaf-tip shape is called ‘mucronate’), the short triangular ends to the ‘petals’ (strictly speaking these are actually called corolla-lobes), and very tiny prickles on the leaf-margins, all of which point forward.

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Kingsweston Down

I visited Kingsweston Down yesterday: this is the large area of limestone grassland that runs along the top of the ridge which extends southwest from the Blaise Castle estate. Both the north and south sides of the ridge are covered in woodland, so the whole area is quite sheltered. In some places the grassland is nothing to write home about, but there are some quite extensive patches which are either dominated by Upright Brome (Bromus erectus) or rich in herb species, or both.

One of the most abundant herbs at the site is Yellow-rattle (Rhinanthus minor), in the left-hand photo below. This is a classic indicator of good-quality grassland: it’s a common species of old hay meadows, for example. Yellow-rattle is partially parasitic on the roots of grasses. As you can see in the photo, after flowering the calyx which surrounded the flower inflates: inside, the seeds which develop are loose, and when the plant is blown by the wind, they make a rattling noise inside, hence the plant’s name.

 Yellow-rattle  Common Spotted Orchid

The right-hand photo is of a Common Spotted Orchid (Dactylorhiza fuchsii), one of four growing together in one part of the site. Common Spotted Orchid is our commonest orchid, and colonises new sites readily, liking both grassland and woodland edges, so isn’t particularly indicative of a good quality site, unlike many other orchid species. This individual is a little on the pale side, prompting thoughts of the rarer Heath Spotted Orchid (Dactylorhiza maculata), but the shape of the lower lip, with three more or less equal-sized lobes confirms that this is Common Spotted.

Avon Wildlife Trust previously managed the site, and then it was in better condition, with shorter grassland supporting species such as Restharrow (Ononis repens) and Harebell (Campanula rotundifolium). Today the grass here is quite long, and these species are probably crowded out.

The site can be accessed either from the Blaise Castle estate itself, or from footpaths leading in from Coombe Dingle to the south. Here’s a map: