Buckinghamshire: Prestwood to Naphill: Chiltern Gentian & Sedges

19 August 2011   Walkers & Riders Map for Prestwood & Kingshill*

                             OS Explorer 172 Chiltern Hills East

Length: All day

This walk was our second one in search of good Chiltern gentian sites.  The added bonus was a chance to look at some local sedges and to be able to compare them (OK, not everyone’s cup of tea!).

We started at Lodge Lane, Prestwood SP873000.  In the grass verge on the south side of the road, at the western end, the long-established thrift Armeria maritima was just finishing flowering (see Post for 2 July 2011).  We crossed Wycombe Road at the end of Lodge Lane.  The grass verge here has corky-fruited water-dropwort Oenanthe pimpinelloides, spilling out from its only county site. It has spread to a number of points (depending on where the verge is cut), from its main location in an orchard and pasture-field on the other side of the hedge (also see Post for 2 July 2011).  We found a dozen plants, one still in flower, the rest in fruit, on the left hand side of the house entrance.  They are easily recognised in fruit from other umbellifers by the stiff thick pedicels.  There is no pavement on this side, so we re-crossed the road to go south.  At the church we crossed again and went through the churchyard, where there was burnet saxifrage Pimpinella saxifraga, common knapweed Centaurea nigra, heather Calluna vulgaris and harebell Campanula rotundifolia (where it escapes mowing beneath the yew trees Taxus baccata).  In the lower churchyard was dark mullein Verbascum nigrum.  We left on the right-hand side into the footpath and down into a pasture known as Prestwood Park, walking under the Lucombe oak Quercus x crenata, which was now bearing small bristly acorns reflecting the fact that turkey oak is one of its parents (see Post for 2 May 2011, which also included this part of the route). 

Lucombe Oak acorns

Common blue and meadow brown were flying.

          The footpath continues west through Lawrence Grove Wood, across cultivated land, and then steeply down through Meadsgarden Wood (male roe deer noisily barking in competition) and to Hampden Road.  Here it is necessary to walk along the narrow road south the length of one (long) field to Prestwood Picnic Site and Local Nature Reserve on the left.  We took the path up the chalk slope that starts at the notice-board behind the picnic benches.  Still flowering at this date were wild parsnip Pastinaca sativa, marjoram Origanum vulgare, ox-eye daisy Leucanthemum vulgare, wild basil Clinopodium vulgare, rest-harrow Ononis repens, field scabious Knautia arvensis, small scabious Scabiosa columbaria, eyebright Euphrasia nemorosa, milkwort Polygala vulgaris, burnet saxifrage, and wild carrot Daucus carota. 

Marjoram at Prestwood Picnic Site

At a small scrape on the left was the first patch of Chiltern gentian Gentianella germanica, some plants tall and bushy (biennial form), others small with single terminal flowers (annual form).  

Chiltern gentian at Prestwood Picnic Site

Chiltern gentian, annual form

Near this pit and bare earth under a young oak is a little basil thyme Clinopodium acinos. 

Basil thyme

All three knapweeds are here: greater, common and chalk Centaurea scabiosa, nigra & debeauxii.  Further up the slope on the right is the largest patch of Chiltern gentians, often over a hundred spikes, with numerous small first-year versions, some with only 4, not 5, petals.  Here a few yellowworts Blackstonia perfoliata and pink common centauries Centaurium erythraea were still flowering.  Crossing the slope northwards to the path on that side of the reserve we encountered many clustered bellflowers Campanula glomerata and the fruiting stems of both agrimony and fragrant agrimony Agrimonia eupatoria & procera.  The latter tend to be larger and more robust, but the surest means of identification is to use the fruits, which for fragrant agrimony are less clearly lined on the basal portion, above which the bristles bend back before rearing upwards, appearing more bushy, whereas in common agrimony the lines are sharply indented and the bristles are vertical.  

Fragrant agrimony fruits

Butterflies here included green-veined & large whites, small copper, brown argus, common blue, meadow brown, and hedge brown. 

Female common blue

On the marjoram and other flowers were several large handsome hoverflies Volucella inanis, once limited to the London area, but now becoming more frequent in this area.

Volucella inanis

Having circled the slope we left the reserve and continued south down Hampden Road
a little way and then turned left up Perks Lane.  After housing finished on the left there was some creeping Jenny Lysimachia nummularia well-established on a bank on the right side of the road.  

Creeping Jenny

On the bend at the top there was also a small amount of grey sedge Carex divulsa divulsa on the right-hand bank, one of our target sedges for the day, growing among wood melick Melica uniflora which is abundant along the dark road-banks here.  The other sub-species, Leer’s sedge Carex divulsa leersii, also occurs in this region.  It is stiffer, the fruiting stems not bent over flexibly like grey sedge, the fruit clusters are closer together, the individual nuts a deeper brown and spreading to give a more “prickly” look.  There are a few clumps of the Leer’s sedge in the corner of the pasture where the footpath left Meadsgarden wood, at the edge of the wood, but our route would take us past another site for this sedge.  (See the article by Foley & Porter “Notes on the morphology of Carex divulsa (Grey Sedge)” in the BSBI Newsletter, April 2008, for a study which includes the Perks Lane site and others on this walk.)

          Just above the bend is an entrance to Longfield Wood, where there was a large clump of wood sedge Carex sylvatica, a very distinct sedge because of its long narrow drooping pedicels.  It is one of the commonest of the woodland sedges in this area on the chalk, along with remote sedge Carex remota, which is also common on more acid soils.  Remote sedge is similar to grey sedge but has much more separated fruiting clusters lower on the spike and the lowest bract is extremely long, usually exceeding the whole spike.  As we walked along the upper path through Longfield Wood (keeping to the left) we passed much of both wood and remote sedges.  Also at the side of the path was yellow pimpernel Lysimachia nemorum, a native ancient woodland indicator, which is a more delicate prettier plant than the garden escape creeping Jenny.  Wood millet Milium effusum and wood meadow-grass Poa nemoralis are common along here.  The wood also has wood barley Hordelymus europaeus along some of the lower paths.  These grasses are ancient woodland indicators, as is enchanter’s nightshade Circaea lutetiana, which is very common along this path.  It was no surprise to see speckled wood flying here to add to our list of butterflies.

          The path continues along the top of Longfield Wood and into Hatches Wood, which follows without any clear boundary.  Near the end of Hatches Wood we reached a wooden fence separating a rather remote house and garden.  Here we turned right off the path and through an area of beech Fagus sylvatica, littered with branches from recent felling.  After a few yards there is a distinct woodland bank at one time separating the wood from a chalk grassland slope to the bottom the valley (known as Hatches Bank).  Some 50 years ago this was converted to a plantation mainly of larch (Juniper Plantation – was there once juniper here, or was this just a flight of fancy?).  Most of the larch and some other trees have now been removed but it is still mainly scrub and incipient secondary woodland.  The local conservation group Prestwood Nature have recently been trying to restore the grassland by removing the scrub on behalf of the owner, because some of the original grassland flora still survived in small glades, including a good colony of Chiltern gentian.  The slope here is one that has been cleared, resulting this year in an incredible display of the gentians in their hundreds carpeting the site, some of them very vigorous and large, and including hybrids with autumn gentian Gentianella x pamplinii. 

Hybrid gentian

Other plants currently flowering at this rich site were: carline thistle Carlina vulgaris (also responding well to the increased light), dwarf thistle Cirsium acaule, basil thyme, large thyme Thymus pulegioides, field scabious, harebell, ploughman’s spikenard Inula conyzae, common knapweed, and yellowwort. 

Carline thistle

Ploughman’s spikenard

Among the brown carder bees Bombus pascuorum attending the flowers were other bumble-bees with brighter ginger hairs on the thorax and a white tail, the new immigrant tree bumble-bee Bombus hypnorum, now well-established in this area.  As one of the prettiest of the bumble-bees it is most welcome.  As usual round-mouthed snails indicate the quality of this chalk bank and slow-worms are common.

          We left the site to return to the path and walked down to the road at the bottom (Hatches Lane), which we descended to our right.  We passed the wood on our right, followed by two isolated houses and horse pastures.  Just past the entrance to the second house were several clumps of sedge on the right-hand verge and these proved to be Leer’s sedge, at another of the sites mentioned in Foley & Porter’s paper. 

Leer’s sedge

On the opposite side, on a wide verge that has been much disturbed, grew a colourful display of tall corn sow-thistles Sonchus arvensis. 

Corn sow-thistles, Hatches Lane

At the bottom of the lane on the right-hand side is a wall belonging to Lower Warren Farm which has wall-rue Asplenium ruta-muraria and wall pennywort or navelwort Umbilicus rupestris, a western and coastal plant that is extremely rare in this region.  Possibly introduced, it has been established here for decades at least.

          We were now back on Hampden Road, but crossed it and took the footpath directly opposite, which passed between some houses and then through a pasture and a field of maize.  At the second stile we turned left along a footpath down the edge of the field to the road at the bottom (Speen Road).  Here we turned left along the road as far as Stocking Lane on the right.  We walked up this road, and near the top of the slope by the entrance to a small trading estate, there were more clumps of grey sedge.  

Grey sedge

We carried on up the road to Naphill, as we passed near habitations coming across plants such as fennel Foeniculum vulgare and (surprisingly) woolly thistle Cirsium eriophorum. 

Woolly thistle

The latter does not usually occur in this area and these plants, close to houses, were no doubt garden escapes.  The cobwebby calyx and large purple or white flowers make them unmistakeable.  Swallows and house martins were gathering on telegraph wires in the traditional manner, preparing for a journey south to warmer climes – this August having been largely wet and cool one could hardly blame them.  At Main Road, Naphill, we turned left and stopped for a lunch break at The Wheel, a pub set back a little way from the road (reflecting the fact that before this village was as built-up as it is today common-land extended across here and the pub was sited on its edge).  This inn is currently Pub of the Year for the region in the CAMRA Good Beer Guide and serves traditional pub lunches.  

The Wheel

A large black weevil on the window-sill next to our table was a vine weevil Otiorrhynchus sulcatus, a common inhabitant of houses and gardens that can be a crop pest.

          After refeshment we carried on along Main Road eastwards for about a kilometre, past one junction and footpath on a bend, where the road becomes Coombe Lane, and took a footpath on the right (the sign hidden in the hedge on the road-bank, but it is just after houses end on that side) as we started to descend the hill towards Hughenden Valley.  This took us down a sheep pasture that was white with an exuberant display of wild carrot and yarrow Achillea millefolium in full flower.  (As we have mentioned before in these blogs it is sometimes the commonest flowers that provide the most memorable scenes.)  The path enters allotments and goes along the western and southern sides.  By taking the main path from the southern side through the centre of the allotments we found Irish spurge Euphorbia hyberna, well outside its native region. 

Irish spurge

There is also quite a lot of hedgerow cranesbill Geranium pyrenaicum.  The path continues through another field where the margin was thick with unusually tall “dwarf” spurge Euphorbia exigua.  The next field hosts the origin of the Hughenden stream, unfortunately now completely dry.  A couple of willows give away that fact, but there was no sign of water plants, even though when the stream flows there can be an abundance of water-cress.  We crossed this field to the gate leading on to the roundabout on the A4128 where it turns up Cryers Hill.

          We walked up Cryers Hill on the left-hand side, where a pavement is separated from the road by a wide grass verge, although this is no protection from the noise of the traffic, which is rather wearing on the walk up here.  There is, however, a reason for persisting, as there is a rare plant long-naturalised on this verge as the road, half to two-thirds of the way to the top, bends slightly to the right.  This is longleaf Falcaria vulgaris.  It is established along quite a long section and is usually easy to spot with its large scrambling bushy stems spilling across the grass and even over the kerb.  It has for several decades been left by the verge-cutters, but this year the whole colony had been cut to the base, with only a few small flowering and fruiting stems escaping the pogrom.  This plant seems to have been an early victim of the financial cuts, which have resulted in “rationalisation” of the road-verge cutting regime, during which information about the preservation of this plant seems to have been lost.  We hope it will survive this vandalism and that the council can be persuaded to take better care of it next year.

Longleaf, a flattened plant resurrected

In the village of Cryers Hill we took a digression east (along Cryers Hill Lane) to the vicinity of Hazlemere, where we were interested to see if the plant it was named after Corylus avellana still abounded.  Walking a lot of the edge of the now extensively built-up area (basically an extension of High Wycombe) we could at least establish that hazel does still grow in hedges on its boundary, but in no more greater proportion than it does anywhere else!  It is a mystery why a place should be named after a common plant that one would have thought hardly served to distinguish it from anywhere else, but perhaps the original village was a source of hazel stakes for fencing or nuts to trade.

Nuts!

The main road at Cryers Hill leads straight back to Prestwood, if you can stand the noise of traffic, but there is one difficult section with no sidewalk between Great Kingshill and Prestwood.  Available footpaths take you on rather circuitous routes, either westwards via Pipers Corner School and retracing Hatches and Longfield Woods, or eastwards into Great Kingshill and to Heath End, where a path leads through Crooks and Peterley Woods and ultimately back to Lodge Lane.  We chose the latter, although there is little of botanical note along the way.  A brief rest may, however, be made at Cockpit Hole, a deep pond recently restored and improved, where we saw gipsywort Lycopus europaeus, great willowherb Epilobium hirsutum, purple loosestrife Lythrum salicaria, reed Phragmites australis, reed sweet-grass Glyceria maxima, bulrush Typha latifolia, and water mint Mentha aquatica.  We also passed through Peterley Manor Farm where a piece of cultivated ground just before the farm buildings has small nettle Urtica urens, creeping yellow-cress Rorippa sylvestris, and shaggy soldier Galinsoga quadriradiata.

*Available from Amersham (Fox’s), Great Missenden (Roald Dahl Shop, Station Kiosk & Taxi Office), Little Kingshill (The Full Moon), Prestwood (King’s Head, Peterley Manor Farm Shop, Polecat, Post Office, PEM Newsagents)