21 August 2012 OS Explorer 171: Chiltern Hills West
Length: All day.
We parked at Cowleaze Wood SU725955. We walked to the north end of this Beech Fagus sylvatica wood on rather acid clays dominated by Tufted Hair-grass Deschampsia cespitosa and crossed the road to the path that enters the Bald Hill section of Aston Rowant National Nature Reserve. This reserve covers the best of the Chiltern chalk escarpment grasslands and we would spend the whole morning exploring much of it before we engaged in any extensive walking, as there is so much to look for here. At the entrance from the road a handy leaflet with a map is available and we initially took the northern arm of what is labelled there as “Sheepcote Lane Walk” (orange) to the circular “Linky Down Walk” (blue dots), going NE then NW.
Map of Aston Rowant NNR showing trails
(from Natural England leaflet)
This first crossed a plateau meadow, still on the clay, with Corn Mint Mentha arvensis, Hop Trefoil Trifolium campestre, Wild Basil Clinopodium vulgare, Red Bartsia Odontites vernus, Common Centaury Centaurium erythraea, and Lady’s Bedstraw Galium verum.
Corn mint – popular with flies
Wild basil
We then walked through a sheep pasture where the grass was shorter and less floriferous, although we did see Harebell Campanula rotundifolia. After this the trail turns left to descend the hill on the chalk.
Instead of following the trail down through a double hedgerow we entered an open gate leading to the steep SW-facing slope where we could see scattered stands of Juniper Juniperus communis.
Juniper on Bald Hill
On southern chalk down-lands juniper is endangered because it rarely seems to regenerate naturally, leaving an increasingly ageing stock. There are some fenced enclosures to prevent grazing of young juniper and in one of these we noticed a small plant that looked healthy enough as a contribution to a new generation. The rest of the slope is winter-grazed to keep the grass short and encourage the rare turf flora. The flowers in turn attract a large range of butterflies and these were evident even though the day was overcast, with Meadow Brown, Small Heath, Common and Holly Blue, Red Admiral and Brimstone.
Common blue on wild basil
Dwarf thistles
Autumn gentian
Squinancywort
Among the harebells were a few completely white specimens.
White harebell
Additional butterflies here were Brown Argus and several of the rare Silver-spotted Skipper.
Silver-spotted Skipper on Small Scabious
Near the bottom of this section, which we followed NW parallel to the trail, we found another gate to regain the latter. Here we added Blue Fleabane Acer erigeron to our list. The track descended through another floriferous long-grass meadow along the edge of the reserve to Hill Farm and the beginning of a paved road. 100 metres along this road we met the Lower Icknield Way
Blue fleabane
M40 crossing Ridgeway
After the motorway we came to a track on the right leading up into the Beacon Hill section of Aston Rowant reserve, but we first went on a short distance to examine the narrow wood on the left-hand side of the Rigeway, Lewknor Copse. Here Spurge-laurels Daphne laureola were everywhere with their evergreen leaves, although they had dropped their berries, and abundant woodruff Galium odoratum.
Spurge laurel
Despite the wet summer the ground here was very dry and the spurge-laurels seemed to be suffering except where the shade was deepest. We also found one clump of narrow-lipped orchids Epipactis leptochila here. They had just finished flowering but the dried petals on the tip of the lowest developing seed-pod still showed the narrow central lip after which it is named.
Narrow-lipped helleborine in seed
After examining this copse we returned to take the path up into the reserve again. This led to a steep slope of short grassland with abundant Clustered Bellflower Campanula glomerata, which we followed to our left.
Botanically rich grassland, Beacon Hill , with clustered bellflower
At the top of this near the path and wherever there were bare disturbed patches the increasingly rare Pale Toadflax Linaria repens was abundant: it was good to see it doing so well.
Pale toadflax
Other plants of the bare chalk scrapes were Wild Mignonette Reseda lutea and Wild Candytuft Iberis amara, the latter unfortunately now only in seed.
Wild mignonette with Wild candytuft seedheads
We also saw Dropwort Filipendula vulgaris, now in seed, and some Yellow Rattle Rhinanthus minor. Clustered bellflower continued common along here among more autumn gentian, rock-rose and squinancy-wort. Scattered junipers looked wind-swept and age-worn.
Old juniper, Beacon Hill
In a patch of scrub we glimpsed a Dark Bush-cricket which turned out to be camera-shy. Equally shy was a Mistle Thrush we frightened up from among the Hawthorn Crataegus monogyna bushes. By the path skirting the hill-top we saw Ploughman’s Spikenard Inula conyza. We eventually came across a minor path going to the peak of the hill, on which we came across another decreasing plant, Frog Orchid Dactylorhiza viridis. These were again in seed, having been at their best about a fortnight earlier.
Frog orchid
Nearby was a white specimen of autumn gentian.
White autumn gentian
From the top we continued along a track going SE along the side of Beacon Hill to the reserve car park. This passes through an octagonal concreted area where there used to be a visitor centre. Here were some seats overlooking the view where we ate a quick lunch, the motorway partly shielded by trees planted below but, if out of view, certainly not out of earshot.
M40 from Beacon Hill
The pretty yellow-and-black hoverfly Xanthogramma pedissequum was keen on the nectar of Wild Carrot Daucus carota at our feet.
Hoverfly Xanthogramma pedissequum
From the car park we walked the minor roads to the A40. The woods here were full of Wood Barley Hordelymus europaeus, with some Wood Melick Melica uniflora on roadside banks. Just out of the woods, where we joined the Cowleaze Wood road, was a huge sarsen stone, presumably left after weathering of the clays around it, as it seemed much too large to have been shifted.
Large sarsen
We proceeded NE to the A40 road, where there was a large patch of meadow cranesbill at the corner. We crossed and continued on the minor road, past some Hedgerow Cranesbill Geranium pyrenaicum, until it bent sharply left and we continued straight on by means of a bridleway. Kingston Wood on the left again had abundant wood barley.
The bridleway bends right, keeping to the edge of the wood, and after half a kilometre we took a footpath angled back left to regain our original direction through Kingston Wood. Although this is legally a “footpath”, it is heavily used by horses and cycles, as it connects two bridleways. No attempt ever seems to be made to police these paths and prevent such inappropriate use. The woods along this path are quite moist and contain some large ferns, including not only the common Male and Broad Buckler Ferns Dryopteris filix-mas and D. dilatata, but also some much rarer in the eastern half of the country, Borrer’s Male Fern Dryopteris borreri, with shaggier mid-ribs to the fronds and a black patch at the base of each pinna, and Lady Fern Athyrium filix-femina.
Borrer’s male fern
Lady fern
As we continued through the beeches of Crowellhill Wood we passed one splendid spike of Violet Helleborine Epipactis purpurata sheltering under a holly bush Ilex aquifolium.
Crowellhill Wood
Violet helleborine
It may have been this slight protection that prevented it becoming a bitten-off stem like all the other specimens we found, the victims of over-numerous deer (muntjac, roe) in these woods. We also noted some Tutsan Hypericum androsaemum.
Eventually we reached then end of the road at Crowell Hill and took the bridleway descending the scarp again through Crowelhill Wood, where the vegetation was sparse and dominated by Giant Fescue Festuca gigantea and False Brome Brachypodium sylvaticum. At the end of the wood we made our way through a rough field with yellow-wort and common centaury to reach the Ridgeway again. At this corner there was a gate into Oakley Hill Nature Reserve (Berks, Bucks and Oxon Wildlife Trust). Above a tall grass meadow with lots of Common Blue Damselflies, we came to a grazed slope with a mixture of short and long grass.
Common blue damselfly
An immediate contrast with the grasslands we had traversed at Aston Rowant in the morning was an abundance of Chiltern Gentian Gentianella germanica instead of autumn gentian. There did not seem to be the mixture of the two species as often occurs. The Chiltern gentians stood out by reason not only of their larger growth and widening calyx but also the dark, purplish leaves and deeper purple flowers.
Chiltern gentian
Many of the chalk flowers we had recorded at Aston Rowant grew here as well, especially lots of clustered bellflower, small scabious, carline thistle, and blue fleabane.
Carline thistle
There was also common eyebright, although here the latter was mixed with larger-flowered Chalkhill Eyebright Euphrasia pseudokerneri, although both were variable in flower-size and there seemed to be many intermediates.
Chalkhill eyebright
The chalkhill eyebright was best identified by the long bristle-like tips to the teeth of the flower-bracts, coupled with at least some larger flowers (there were often smaller ones on the same plants). “Pure” Euphrasia nemorosa actually seemed to be relatively infrequent. There was also Large Thyme Thymus pulegioides here, having so far seen only wild thyme at Aston Rowant.
We were surprised to see a large distinct patch of purple grass which looked like Wood Small-reed Calamagrostis epigejos and turned out to be so, despite being in open grassland instead of the familiar woodland habitat. Apparently this grass has in recent decades started to appear in such open situations. Here it looked as though it had the capacity to be quite invasive and dominating, although of course sheep grazing, used by the Trust over the winter, would prevent it spreading.
Oakley Hill reserve, with purple wood small-reed patch at right
We added Small Copper and Gatekeeper to our butterfly list and a pure white clustered bellflower to our “albino” list for the day.
Below the reserve lie the Chinnor chalk quarries, their blue waters inhabited by tufted duck, coots and Canada
Chinnor chalk quarry
This reserve was the furthest point NE we intended to reach today and we returned to the Ridgeway for an easy and straight walk back to the vicinity of Aston Rowant. Although the vegetation along here was not remarkable, we did see some tutsan, Alsike Clover Trifolium hybridum, and Wormwood Artemisia absinthium, the latter conveniently near its relative Mugwort Artemisia vulgaris for its greyer less sharply lobed leaves to be readily discernible – its strong smell bringing immediate confirmation.
Wormwood leaves
When we reached the point near Hill Farm where we first came down to the Ridgeway we continued for another half a kilometre to the footpath on our left that goes south across a field and then a wood before turning abruptly SE along the outside of the wood (some Long-stalked Cranesbill Geranium columbinum and Field Madder Sherardia arvensis in the grazed grassland here) and going uphill to Bald Hill, this time along the bottom of its SW-facing slope. Here in the nature reserve once more was a huge population of Chiltern gentian, whereas we had seen only autumn gentian north of the hill.
Chiltern gentian on Bald Hill
There Autumn gentian was accompanied by wild thyme, as against the large thyme that seemed to be most frequent here. Here was also some Rest-harrow Ononis repens. A bare-topped anthill at last revealed, among some large thyme, a few spikes of the rare Mat-grass Fescue Vulpia unilateralis, which we had been seeking all day, having seen it in the reserve five years before. Now, later in the year (it flowers May-June), it was reduced to tiny dry yellow stalks, but its one-sided small flower-spikes were still identifiable. We climbed up the steep slope through dense gentians and other flowers, including more chalkhill eyebright, frog orchids, and a small Common Spotted Orchid Dactylorhiza fuchsii still visible in seed. A caterpillar feeding on hairy rosette leaves of what may have been devilsbit scabious (although we saw no flowers of this plant) was the club-horned sawfly Abia sericea.
Larva of club-horned sawfly
By then we could see the rain that had threatened all day coming from the south along the escarpment and it caught us as we reached the top of the hill and regained the path to Cowleaze Wood, arriving back at the car wet-through, but pleased with the day’s discoveries and relieved that the storm had not struck much earlier, as a favourable weather forecast had lured us into venturing out without wet gear!
I am mainly interested in insects, but it is lovely to find the names of the flowers too in your very interesting blog. Thankyou.
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