Monthly Archives: July 2013

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.

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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).

Upright Spurge in the Wye Valley

Yesterday I paid a visit to Ravensnest Wood in the Wye Valley, to see one of the rarest plants found in this area, Upright Spurge (Euphorbia serratula). As a native species, Upright Spurge is found in Britain only in an area centred on the Wye Valley and the Forest of Dean. It is also naturalised in scattered locations, mainly in southern England. Although a rare plant in Britain, globally, it is found eastwards to central Asia.

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Upright Spurge’s habitat is woodland on limestone, but not the dense dark parts: instead, it is found in the open, and does best on disturbed ground. Newly created forestry tracks and clearings are where it does best, particularly if limestone chippings are laid. Ravensnest wood held 500 plants in 1997, presumably when the access track there was very new. Yesterday I counted a much more modest 17 plants: along much of the track, grassland had become established, crowding the spurge out, and it was only present in areas where there was still very sparse vegetation. Here is a map of the location:

According to Sell and Murrell’s Flora of Great Britain and Ireland, the most authoritative reference work on Britain’s flowering plants, Upright Spurge occurs in only about 24 British localities. The densest concentration is around Tintern and so, predictably, it has acquired the local name “Tintern Spurge”. Other locations in the Wye Valley are spread throughout a 10km-long stretch from about Wynd Cliff in the south to around Whitebrook in the north. In the Forest of Dean, its main concentration is just to the west and north of Lydney. Much further east, it grows in Highnam Woods, just west of Gloucester. West of the Wye Valley, it occurs in Chepstow Park Wood and in Coed Wen Wood, east of Newport (note that the Grid Reference in Trevor Evans’ Flora of Monmouthshire for this last site is incorrect).

Seeds of Upright Spurge can lay dormant in the soil for years, possibly decades, and so if a site becomes overgrown, fresh disturbance can boost the population. At Highnam Woods, the RPSB does just that, using a rotavator, and so the population there is likely to be secure. At other sites, Upright Spurge has declined or even vanished, but could no doubt be encouraged to flower again if similar techniques were applied. How about it, Gwent and Gloucestershire Wildlife Trusts?

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.

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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.

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Green Sandpiper

Autumn is here: the first of the post-breeding shorebirds are on their way south. At Slimbridge, while I was watching the Spoonbill, there were at least six Green Sandpipers (Tringa ochropus) feeding on the edges of the same pool. I was going to illustrate this post with my own photos, and then Vic Savery sent me this excellent shot:

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Green Sandpiper, 1 July 2013, Slimbridge, Gloucestershire, Vic Savery (naturenutz.net)

Green Sandpiper is the earliest of our sandpipers to appear on southbound migration, always being seen somewhere locally from the end of June onwards, so no need to panic about winter being on the way just yet. Any freshwater wetland with reasonable areas of exposed mud will be graced by Green Sandpipers over the next few months. The birds turning up at the moment are adults, whereas juvenile birds will occur from August onwards (a pattern common to most migrant shorebirds). Green Sandpipers also overwinter in the region in moderate numbers, tending to inhabit shallow slow-flowing streams and ditches and marshy sites.

Green Sandpipers nest in bogs from Scandinavia eastwards through Russia. Unusually for a shorebird, they nest in trees, in disused birds nests. Occasionally, pairs nest in Scotland. A lookalike species, Solitary Sandpiper (Tringa solitaria), replaces Green Sandpiper in North America. They have occured in southwest England after Atlantic storms in autumn several times, usually on the Isles of Scilly, but there was one in Devon a few years ago, so it’s possible that one could turn up near Bristol one day.

Here are a couple of my own Green Sandpiper photos as well, showing a Slimbridge bird in some different poses, and highlighting how birds can look different in different lighting conditions. You can also see, by looking closely at individual feathers, that this is a different bird from the one Vic photographed.

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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:

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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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