Category Archives: Grassland

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.

ALT2 ALT1

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.

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:

007

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.

002 004

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:

The Avon Gorge: Bristol’s botanical bucket-list site

073 021

On the western edge of the city of Bristol is a nationally important site for wild plants. The Avon Gorge is home to over 500 plant species; as well as whitebeam trees which are found here and nowhere else on Earth, the gorge has two plant species – Round-headed Leek (Allium sphaerocephalon) and Bristol Rock-cress (Arabis stricta) – that are found nowhere else in Britain, and over twenty other nationally rare or scarce species. Peter Marren, in his book Britain’s Rare Flowers listed it as one of the top four sites in England, alongside Upper Teesdale, the Lizard in Cornwall, and the East Anglian Breckland. There can’t be many British botanists on whose bucket-lists a visit to the Avon Gorge doesn’t feature.

Given that I live fifteen minutes away by car from the gorge, you would have thought I’d spend vast amounts of time there each summer and would know the place inside out. In fact, I have tended to spread myself much more equally across the city’s wildlife sites, and so to date haven’t really given the gorge the attention it deserves. Now that I have this blog to write, something tells me that will change.

This afternoon I explored the Black Rocks area of the gorge, which is below the viewpoint on Bristol Downs called Sea Walls (see the map below for the location). The viewpoint is surrounded by sheer cliffs on three sides, but part-way down on the southern side, these give way to a limestone grassland slope with scattered rocky outcrops, altogether covering about a quarter of a hectare. I climbed the steep path which runs up the slope from the car park by the A4 Portway road. The photos at the top of this post show this part of the gorge viewed from the car park, and a close-up of a small part, to give you an idea of the species-richness of the grassland here.

Here are some of the plant species I photographed today. Going clockwise from top left, we have Basil Thyme (Clinopodium acinos), Common Rock-rose (Helianthemum nummularium), Bloody Crane’s-bill (Geranium sanguineum) and Fairy Flax (Linum catharticum).

023 004
031 040

Common Rock-rose and Fairy Flax are widespread species in limestone grassland sites around Bristol, By contrast, Basil Thyme, although found widely throughout the gorge, has been recorded at only one other site in Bristol, near Blaise Castle, and at only about five other sites surrounding the city, Slightly farther afield, it is more common in the Mendips, where its rocky limestone grassland is in greater supply, and also on the Cotswolds and Salisbury Plain.

Bloody Crane’s-bill is the rarest of these four species locally. Other than in the Avon Gorge, it is only found as a native species in Cheddar Gorge and in the Wye Valley, although it also occurs as a garden escape or a deliberate introduction in a handful of places. Unlike Basil Thyme, whose British range is centred on south-eastern England, Bloody Crane’s-bill is a more northern plant; Bristol is on the south-eastern edge of its native range in Britain.

Bristol’s new mayor, George Ferguson, has recently suggested that the Avon Gorge could be put forward to UNESCO as a proposed World Heritage Site, although interestingly, only on cultural grounds, because of the presence of the Clifton suspension bridge, rather than because of its natural features. Britain’s current suite of World Heritage sites only contains one location that qualifies under both cultural and natural criteria (the island of St Kilda off the northwest coast of Scotland), but I think a good case could be made for the Avon Gorge too. See what you think: the criteria are here.

Stockwood Open Space

Stockwood Open Space is a large area of land between Brislington and Stockwood, on the south-east edge of the city. It covers the slopes which lead down from the Stockwood plateau, and some flatter ground below these. Much of the site is grassland or rank vegetation, but there are also some excellent overgrown hedgerows, bushes, and strips of woodland. Here are some photos to give you a feel for the place:

017 008

The meadows come into their own later in the year. At this time of year there are fewer plants in flower, but here are two of the more conspicuous species.

Cowslip (Primula veris):026 Bugle (Ajuga reptans):042

Here’s the location on a map. The site stretches from Whittock Road in the west to Scotland Lane in the east. I usually park at the northeast end of Stockwood Road and walk in from there.