Category Archives: Habitat types

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.

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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.

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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).

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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.

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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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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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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.

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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:

Beautiful Demoiselles

Vic Savery sent me these excellent photos of Beautiful Demoiselle (Calopteryx virgo), which he took at Three Brooks Nature Reserve in Bradley Stoke yesterday. Demoiselles are our largest damselflies, and one of our most noticable and easily-recognised, and like the Common Clubtail I featured in an earlier post, mainly river-dwelling species.

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Beautiful Demoiselle, 14 June 2013, Bradley Stoke, Bristol, Vic Savery (naturenutz.net)

There are two species of demoiselle in Britain; Banded Demoiselle (Calopteryx splendens), the other species, has a narrow dark patch across the wings in males, with extensive clear areas at both the base and tip, and has a blue rather then blue-green abdomen. Female Bandeds are more similar in appearance to female Beautiful Demoiselle, but with green-tinged rather than brown wings. There are other species of demoiselle in continental Europe, including the Copper Demoiselle (Calopteryx haemorrhoidalis) with a copper-red abdomen.

Beautiful Demoiselle prefers faster-flowing streams with stony riverbeds, whereas Banded likes slower-flowing muddier-bottomed rivers; however the two are often found together, indicating some overlap in the types of river they prefer. Ther British distributions differ: Beautiful Demoiselle is mainly found in Wales, southern and western England, with an outpost in western Scotland, whereas Banded Demoiselle is found throughout England and Wales but only just makes it into southern Scotland.

Around Bristol, both species are found on many of our rivers and streams, including the Avon, Chew, Cam, Wellow, Yeo, and both the Bristol and Bath River Fromes. They are also often found away from rivers (e.g. around ditches on the North Somerset levels, or at ponds and lakes throughout the region).