Ecological Flora of theCentral Chilterns

Book III: Spore-bearing Plants

Adder's-tongue fern, Prestwood Picnic Site

Book III (Section 10)Spore-bearing plants

In evolutionary terms these are the earliest and most primitive of our plants. The shed spores develop in a film ofwater into tiny green plants called gametophytes. These produce small male sperm cells and larger female eggcells, the former maturing first so that they will fertilise the egg-cells of gametophytes other than their parentalones by travelling through the film of water, ensuring cross-fertilisation. They are therefore more dependent on awet habitat for reproduction than the seed-producing plants.

Frosted fronds of male fern, December

Family: Lycopodiaceae (Clubmosses) 10.2

Stag's-horn clubmoss Lycopodium clavatumThis inhabitant of heathy woods was last recordedlocally in 1974 in Monkton Wood and in 1973 in LodgeWood (in both cases by the late Ted Byrne). It hasnot been recorded anywhere in the Chilterns orBuckinghamshire since 1974, when it was alsorecorded in Hillock Wood, just outside our area butneighbouring Monkton Wood. It must therefore beconsidered extinct in the Chilterns, as it is fromvirtually all the lowlands, it remaining common only inthe north and west of Britain. The location in LodgeWood was carefully checked in 2001, as it was clearlyidentified by Mr Byrne, who saw six plants growingunder beech with heather beside forestry ruts. Afew plants of heather survived, although they wereattenuated by the lack of light consequent onincreasing conifer cover, and these have also sincedisappeared. The plant was more extensive inMonkton Wood, where Mr Byrne saw it at threeseparate locations. One small patch in 1973 underbeech with heather and heath bedstraw was notrediscovered in 1974. In 1974 there was one 25m-square patch under young beech and conifers wherethe clubmoss was said to be "abundant" and nineplants under regenerating beech by open tracks atanother site. It appears likely that increasing shadewas the reason for its demise there, just as it clearlywas in Lodge Wood.

When producing spore-bearing cones stag's-horn clubmoss is unmistakable, although purelyvegetative procumbent shoots can easily beoverlooked as moss.

(There is a record in BMERC of fir clubmoss Huperziaselago from Lodge Wood in 1977. This is unlikely to haveever occurred in our area and must have been a clerical oridentification error for Lycopodium clavatum . Druce(1926) does not mention stag's-horn clubmoss for ourarea, so it is likely that it always existed in small quantity,probably varying according to alterations of light throughforestry operations.)

Stag's-horn clubmoss growing in Scotland

Family: Selaginellaceae (Lesserclubmosses)Krauss's (Mossy) clubmoss Selaginella kraussianaDiscovered by Patricia Strugnell for the first time in Bucks in2017, naturalised in a garden at a former farmhouse onChurch Lane, Great Missenden. This tropical species, which isvery moss-like, is sometimes used as ground cover and mayalso be introduced accidentally with pot plants from gardencentres. It is creeping, well-branched, rooting as it spreads,and thus mat-forming, and in sheltered situations survivingour winter. It is also well established at Savill Gardens,Windsor. The leaves are in four ranks, two larger onespatent, two half the size more or less appressed to the stem(see picture below).

10.3

Mossy clubmoss showing 4-ranked leaves

Family: Ophioglossaceae (Adder's-tongues)Adder's-tongue Ophioglossum vulgatumThis rare plant has been recorded at only seven sites in ourarea, of which only two are probably extant. It was notmentioned by Druce (1926) and was probably always scarce.It is dependent on undisturbed established grassland thathas not been fertilised. Locally it occurs on thin chalk soilsand in this situation remains a small plant, just a fewcentimetres high, much lower than the maximum 30cm ormore leaf-blade given in Stace (2010).Identification Unmistakable low plant easily overlookedwhen growing amongst grass. From the base of a single ovalleaf-blade appearing in May arises an unbranched fertilespore-bearing stem that ripens yellow June-July.Notable sites Currently known only at Prestwood PicnicSite, where it was discovered by Peter Daltry in 2011, andin similar native chalk grassland in the back garden of ahouse on Perks Lane, on the hillside opposite to the PicnicSite (George Lewis, first seen 2004). The fact that theseare very recent discoveries in well-explored locationsraises the possibility that the plant is a recent arrival byspores from some other nearby site so far undiscovered.All other records are from the 1960s-1980s. In the 1980sit was seen in grassland near Naphill and Speen, but the1960s records are all from open woodlands that have sinceshaded over (all had been planted to conifers) and are nowunsuitable.Ecological associates No galls or mines are known, and noother associates have been noted locally.

Human associations It was traditionally supposed tohave been used for healing wounds, but, despite theassociation of the name giving it that reputation, itwould have been of no use in curing adder-bites.Derivation "Adder's-tongue" is a directtransliteration of the Latin ophioglossum, referringto the supposed resemblance of the narrow fertilespike to a snake's tongue (although it is not forked).Another folk-name was Christ's spear.

Adder's-tongue at Prestwood Picnic Site

Family: Equisetaceae (Horsetails) 10.4Horsetails were the dominant plants during the Carboniferous era, but they are much less prominent today. Allspecies exude crystals of silica on their stems, making them rough to handle.

Field horsetail Equisetum arvenseAbundant in many areas of Britain, field horsetail is a rare plant with us.Less dependent on water than our other native horsetails, it is typicallyin our area a prostrate weedy plant of rough ground and wasteland. Itmay once have occurred along the River Misbourne when the adjoiningfields were wetter, as Druce (1926) considered it "abundant" in our area.Identification There are two types of growth - sterile grooved (6-9ridges) green stems, upright or sprawling, with bushy simple branches,and pale brownish simple (unbranched) stems topped with spore-producing cones (<4cm) which usually appear earlier in April. The latterhave regular sheaths up the stem with 6-20 dark teeth. I have rarelyseen fertile stems produced in our area, which may explain its scarcity,although the lack of fertile stems itself requires explanation.Notable sites This plant is best seen in the hedge along the boundary ofthe houses on the south side of Green Lane. It also grows in our area byPrestwood Village Hall and in the pavement by the main Missenden roadin Great Kingshill. It is well-established at the Sports Centre car-park(first recorded 1996). In many cases it grows in areas that are regularlycleared of vegetation; although the roots survive, it is rarely allowed togrow to any height. That in Great Kingshill grows only in a prostratedwarf form.Ecological associates None known.Human associations Known as a styptic in folk medicine, it has also beenboiled to produce a fungicide (Mabey 1996).Derivation The name comes from a fancied resemblance of the bushyfertile stems to horses' tails.

Rough horsetail Equisetum hyemaleNative to Britain but not to the Chilterns, this horsetail, also known asDutch rush, may be planted in or by garden ponds. It is extant at onesite in our area, in a garden pond on Orchard Lane, Prestwood. It growssimple unbranched green stems that develop a small cone at the tip. Thesheaths up the stem are black at the tip and the base and paler inbetween and soon lose their teeth. The stems are rougher than any ofour other horsetails and have up to 30 ridges. The stems are useful foremerging dragonfly larvae - see the picture, right, which shows theexuvia of a broad-bodied chaser Libellula depressa.

Water horsetail Equisetum fluviatileThis generally common aquatic horsetail was said by Druce (1926) to be"very common by water" in our region, but I have come across no recordsfor the area. It quite probably once grew along the Misbourne nearLittle Missenden. The green stems are often simple or irregularlybranched, have 10-30 ridges, and pale green sheaths with small white-edged black teeth.

Field horsetail

Field horsetail in prostrate form

Rough horsetail in garden pond, Orchard Lane

Family: Dennstaedtiaceae (Bracken) 10.5Bracken Pteridium aqualinumThis fern is widespread in our area in woodlands on somewhat acidic soil. Druce (1926)said it was "abundant except on chalk, clay". In the first half of the 19th century itwas dominant on much of the common land in our area, growing on the poor soils ofsandy clays at Prestwood, Great Kingshill, Heath End and Denner Hill but these were alllost to agriculture at the time of the Enclosures and (except Denner Hill) subsequentlyused for housing. The current distribution shows that bracken is not averse to clay oreven chalk substrates as long as the soil has been leached, does not get waterlogged,and there is enough light. It can be invasive (eg Hampden Common), spreading by toughunderground root-stocks that are notoriously difficult to eradicate.Identification Our only fern that has its main stalks branched in more or lesshorizontal opposite pairs, these branches forming 2-pinnate fronds, the ultimatepinnules being narrow and wavy edged. It can grow to above head height in latesummer and its tough fronds survive as brown debris through the winter.Notable sites It grows commonly in hedgerows, eg Hampden Road, Nairdwood Lane(south) and by the lane to Denner Farm from the top of Rolls Lane, as well as mostwoodlands (eg Hampden Coppice, Atkins Wood, Sandwich Wood), where it can formextensive patches.NVC In open areas on free-draining acidic soils bracken can form the dominantcomponent of U20 Pteridium-Galium communities, often accompanied by heathbedstraw Galium saxatile, tormentil Potentilla erecta and sheep's fescue Festuca ovina.This would have been one of the communities on the former commons, but this habitathas been lost in our area. It is also the dominant in W25 bracken/bramble underscrubin cleared woodland and under hedges, one of its main communities in our area. Inthese communities it is often accompanied by bluebell Hyacinthoides non-scripta whichcan get away to flower before the bracken fronds unfurl and shade out most otherground plants. It is sub-dominant in W10 oak/bracken/bramble and W16oak/birch/wavy hair-grass woodlands, relics of which survive in our area despite thegeneral replacement of oak by planted beech.Galls Five galls have been described in this country, but none have so far beenrecorded locally and should be searched for.Mines Four leaf-miners have been described, one of which is also a gall-causer. Themines of the fly Chirosia histricina have been recorded locally on bracken (NairdwoodLane).Other ecological associates Although one of our most common plants, bracken has alimited number of invertebrate associates because of its toughness. The moths BrownSilver-line and Small Angleshades feed on bracken as caterpillars and have beenrecorded locally, as has the sawfly Tenthredo colon, which shares this habit. Heathdamsel bug Nabis ericetorum has been recorded on bracken (Atkins Wood) and thesmall fungus Rhopographus filicinus grows on the dead stems of bracken in the autumnand winter. Tracts of bracken make excellent cover for many birds and mammals suchas roe deer and muntjac.Human associations When bracken was abundant on local commons it was collected bycottagers as bedding for themselves and their animals, having the advantage that itwas inimical to fleas. Bracken contains cyanides and may be carcinogenic, so thatformer uses in folk medicine may have been accompanied by some risk, although it hasbeen used as fodder for cattle. The ash from burning green bracken was used to makea fertiliser high in potash and dried fronds can be used as a mulch or cover forvegetable plots. For these purposes bracken was once extensively cut, helping keep itunder control, whereas nowadays its spread is a major threat to conservation.Derivation In Middle English the word was braken and "brake" is still a dialect name;the origin seems to be in Old Norse but the connotations of the term are not known.Varieties Our plant is sub-species aquilinum, which is the common sub-species inBritain except perhaps for the Scottish Highlands.

Bracken, Hatches Wood

Showing veins in pinnulesreaching edge of frond

Young frond

Effects of Chirosia histricina

Family: Athyriaceae 10.6Lady fern Athyrium filix-feminaAn attractive woodland fern, but easily overlooked. It occursoccasionally across our area in ancient woodland and was said byDruce (1926) to be "locally frequent" in the Hughenden and Kingshillareas.Identification The fronds are bipinnate like male fern, ie the mainpinnae are deeply cut into pinnules, which are deeply and finely cut soas to look almost tripinnate, much more delicate and attractive inappearance than the male fern, hence the name, a survival from moresexist times. The fronds can look surprisingly like the pinnae ofbracken. The spore covers underneath fertile fronds are not roundor kidney-shaped, but bean- or half-moon-shaped. The stalks haveonly small scattered scales.Notable sites It grows sparsely in most of our more ancientwoodlands, particularly Piggotts, Monkton, Little Stocking and Gomms,usually along damp rides (eg Angling Spring Wood) and ditch-edges inleached or more acid places.Galls Only two galls are known nationally, of which one is very rare.The other, rolled fronds caused by the larvae of the fly Chirosiabetuleti, is quite common locally.Mines Not known for certain in Britain.Other ecological associates None recorded.Human associations None, which probably shows that the species hasnever been really common.Varieties Lady fern was particularly known in the times of theVictorian fern-craze for its large number of sports. While thisgenetic variability may have been collected out, it may still be worthlooking out for unusual forms.

Family CystopteridaceaeBrittle bladder-fern Cystopteris fragilis

Lady fern

Brittle bladder-fern, Great Missenden

This is a very rare fern in the south and east of Britain and its occurrence in our area, at its only Buckinghamshire(and Chilterns?) site, is a subject for speculation. It may have been brought in with stone used for building, but itmay also be truly native. It has been known for some forty years. Although not recorded by Druce, it could easilyhave been overlooked and it has probably been at its present site for a century or more.Identification The fronds are narrow, delicate, and small (no more than 25cm) and the pinnae well separated.Notable sites Only one currently known, on the walls of Great Missenden Parish Church, where a very smallnumber of plants are protected by railings in a very shady and wet spot, exactly where it was first recorded in1975 by Ted Byrne. It still grows with hart's-tongue and male fern as noted by Mr Byrne, but the hart's-tongue isspreading vigorously and could out-compete the Cystopteris. BMERC records also include a 1980 record by TedByrne from nearby Missenden Abbey. While there is suitable habitat there it has not been found subsequently andit is almost certain that the second record was misallocated on being entered into the records, as Mr Byrne's ownnotebooks in my possession make no mention of a second site, although he made several subsequent visits to thefirst site. He did, however, record it in 1979 on the north-facing wall of Holy Trinity Church in Penn Street (justoutside our area), from which it was subsequently lost through cleaning operations. (Rustyback was lost from thissite in the same way.) The fact that it existed at another site adds some evidence for its being native.Mines Our plants host the fly Chirosia histricina, which also occurs on our commoner ferns.Derivation The "bladders" are the minute bottle-shaped spore-covers on the underside of fertile fronds, whichare soon lost, however, leaving the spore-heaps bare. The stalks are brittle, but this should not be tested, andindeed the plants should not be touched at all, due to their rarity.

Family: Aspleniaceae (Spleenworts) 10.7These are mainly wall-growing ferns.

Hart's-tongue Asplenium [Phyllitis] scolopendriumThis distinctive fern inhabits wet shady places such as north-facing church-walls, chalk-pits and roadside banks,widely distributed but not common (in Druce 1926 it is recorded as "rare" in our area).Identification The fronds are oblong, bright glossy green, up to 60cm long and grow in clusters. The spores lieunderneath the frond in straight diagonal lines from the mid-vein or rhachis. They are quite tough and last wellinto the winter.Notable sites On most churches (especially the Zion Baptist Chapel in Prestwood), but in small numbers becauseof frequent wall-cleaning. Often on railway bridges. Larger colonies may be found along deep lanes with highbanks, especially where chalk comes to the surface - eg Kingstreet Lane, Featherbed Lane, Perks Lane underLongfield Wood, and Broombarn Lane. It has also been found growing in a drain along Prestwood High Street andChurch Street, Great Missenden. It rarely occurs in wet woodland (eg Peterley Wood after the wet winter of2013-14).Ecological associates No galls and only three mines are known on hart's-tongue in Britain. Two of these mines, bythe small moths Psychoides filicivora and P. verhuella have been recorded locally. No other associates have beennoted.Human associations Although hart's-tongue has been used in folk remedies in Ireland and the west of Britain, ithas never been frequent enough in our area to have attracted any particular attention.Derivation The frond is supposed to have the shape of a deer's tongue; it is also called fox-tongue in somelocalities.

Hart's-tongue growing on a stony bank

Wall-rue Asplenium ruta-murariaMuch smaller but still distinctive fern entirely restricted to walls, where it is rather uncommon in our area.Identification Short tufts (to 10cm) of tough branched fronds with wedge-shaped segments which are themselvessometimes divided. Underside of frond covered with pale brown spores.Notable sites This fern is typical of brick railway-bridges all through Great Missenden and can be abundantthere. It occurs more sparsely on church walls because it regularly gets "cleaned" off (eg just one plant on GreatMissenden Parish Church in 2014). It is also established on old flint walls beside Lower Warren Farm, StonygreenCottage, Abbey Farmhouse in the Square, Great Missenden, and very few other places.Ecological associates No galls and the same three mines that occur on hart's-tongue are known on wall-rue butnone have been recorded on that plant locally, nor any other associates.Human associations None.Derivation The fronds are somewhat reminiscent of the Mediterranean herb "rue".

Wall-rue typically growing on railway bridge brickwork

10.8

Young leaves of wall-rue are less divided

Maidenhair spleenwort Asplenium trichomanesAnother small fern restricted to walls in our area,where it is even less common than wall-rue. Druce(1926) considered it "very local, rare" in our area.Identification Tuft of wiry dark brown stalks withthe frond divided into small oblong pinnae.Notable sites This fern used to be found regularlyon the railways bridges with wall-rue, but moresparsely, but it is now rarely found. Recent recordsare from Missenden Abbey and walls in a nearbygarden, the railway bridges at the bottom ofWhitefield Lane (2007, but not there 2014) and nearMisbourne School, a wall in the High Street, andHughenden Valley. A drier climate over the last fewdecades seems to have done this fern no favours.Ecological associates As for other Asplenium spp,but none recorded locally.Human associations None.Derivation The dark wiry stalk is similar to that ofMaidenhair Fern, but it is otherwise quite distinct."Spleenwort" refers to traditional remedies ("wort")for assumed disorders of the spleen, but this seemsto have been an invention of old herbals and the onlydocumented use, like other spleenworts, was forcoughs and similar ailments, probably because of asimilarity of the mucilaginous liquid obtained fromboiling the fronds with the mucus produced in colds(the pre-scientific "doctrine of signatures" or the useof "like against like"). Its use was once well-known,for Alexander Pope references it in his "Rape of theLock": "A branch of healing Spleenwort in his hand".Varieties Our plant is ssp. quadrivalens, the onlyform in chalk districts, differing from forms in thenorth or west and on acid substrates by the shape ofthe pinnae.

Black spleenwort Asplenium adiantum-nigrum 10.9Another fairly small wall-fern almost as uncommon inour area as maidenhair spleenwort. It was notincluded for our area in Druce (1926).Identification This wall-fern is more fern-like thanthe others because of its much more divided "ferny"frond.Notable sites It survives in good numbers on theparapets where Martinsend Lane and Rignall Road goover the railway, but has almost disappeared fromother railway bridges. It no longer grows on thechurch walls (eg Great Hampden) where it onceexisted (if sparsely), except for a single frondunlikely to survive long at Prestwood Parish Church.Ecological associates As for other Asplenium spp,but none recorded locally.Human associations None.Derivation "Black" refers to the base of the stalk,which is green in the rare Green spleenwort A.viride not present in our area.

Rustyback Asplenium ceterachThis very distinctive wall-fern is very rare in our area,where it has long been known from just one site.Identification The frond is divided into connectedlobes, which tend to curl up to prevent water loss in ourclimate. The most distinctive feature is the dark brownspore masses that give it its name, completely coveringthe undersides, particularly obvious when the frondscurl up.Notable sites The flint wall of the ha-ha in the privategrounds of Missenden Abbey.

Rustyback at its one local site

Family: ThelypteridaceaeLemon-scented fern Oreopteris limbospermaRecorded from Monkton Wood in 1974 by Ted Byrne,but not seen in any subsequent surveys. It was notmentioned for our area by Druce (1926). The habitatwas once suitable, however, and there is no reason todoubt the record. It is like a smallish male fern (below)and could easily be overlooked. Its most distinctivecharacter is the lemon scent when crushed. Thenearest extant site to my knowledge is Black Park in thesouth of Buckinghamshire. There may no longer be anysuitable habitat in the Chilterns.

Family: Blechnaceae 10.10Hard fern Blechnum spicantAnother rarity in our area, hard fern is distinctive with itscontrasting fertile and infertile fronds and is restricted toacid soils. Druce (1926) describes it as local to absent inour area, avoiding lime.Identification The fronds are narrow and 1-pinnate withsimple short pinnae. The infertile fronds, rather like a longnarrow polypody (see below), grow in a rosette and soonspread close to the ground. The fertile fronds have verynarrow pinnae, dark stalks, and stand upright in the centreof the rosette.Notable sites It has been recorded in just threewoodlands in our area, but still survives at all of them. It isin smallish quantity on wet clay in Monkton Wood andHampden Common (under conifers), but is quite prolific inparts of Sandwich Wood, where it grows on drier sandy soil.Ecological associates None known.Human associations None.Derivation The fronds are stiff and "hard" to the touch.

Hard fern (2 fertile fronds) in Sandwich Wood

Family: DryopteridaceaeMale fern Dryopteris filix-masOur commonest woodland fern throughout all our woodlands and sometimes walls etc.Identification Robust narrow-ovate bipinnate fronds can stand well over a metre high, often in a shuttlecock-likerosette. The pinnae are green where they meet the main stalk, which is covered, especially towards the base, bypale brown scales, which can be quite dense and obvious in young fronds.Notable sites This fern is so common in woods of all types (wet or dry) that no particular site stands out.Galls The two species noted on lady fern above also apply to male fern. There is also a fungus that can cause thickyellow blotches, but that has not yet been recorded locally.Mines The fly Chirosia histricina and the moth Psychoides filicivora cause mines and have been recorded locally.Other ecological associates The plant hopper Eupteryx filicum has been recorded on male fern in Lodge Wood.Larvae using male fern include Small angle-shades moth and two sawflies Aneugmenus coronatus andStrongylogaster lineata. The number of feeders on ferns is limited by the toughness of the leaves.Human associations I have not come across any.Derivation "Male" in distinction to the smaller, less robust "lady" fern (see above).

Luxurious growth of woodland male ferns Kidney-shaped spore clusters on male fern

Broad buckler-fern Dryopteris dilatataAlmost as common as male fern in our woodlands, andjust as widely distributed.Identification Can be as large as male fern, but easilytold by the tripinnate triangular frond. The scales onthe stem have a narrow or wide black central stripe,often making the stalks look black from a distance.Notable sites As with male fern, this species is socommon that it can be found in any woodland.Ecological associates As for male fern.Derivation A "buckler" is a small round shield, andrefers to the rounded spore-coverings (see picture ofmale fern pinna above). The same reference occurs inthe name "shield-fern" (see below).

10.11

Broad buckler-fern (lower) and male fern (upper)

Young cluster of broad buckler-fern

Rolled shoot-tips on broad buckler-fern caused by fly Chirosia histricina

10.12Borrer's male fern Dryopteris affinis ssp.borreriOld records of Dryopteris affinis often do notdistinguish the sub-species and are therefore difficultto evaluate. Dryopteris affinis affinis, however, is veryrare in our region and it is likely that all plants in ourarea are borreri.Identification Like male fern but with shaggier stalks,the scales being a richer golden or reddish brown. Thestalk at the base of each pinna, where it meets to mainmidrib of the frond, has a more or less conspicuousblack spot, a useful indicator because male ferns canvary in the density of their scales. These attributesare shared with affinis, but it is distinguished from thatspecies by the pinnules, especially those of the lowerpinnae, being more squared off at the end rather thanevenly rounded, while the lowest pinnule on the lowerpinnae has a marked lobe. It also has gradually taperingpinnae, while those of affinis have equal-length pinnulesin the basal half. Borrer's male fern is intermediatebetween male fern and affinis in the density of scales,being less readily picked out by this character. It is abrighter green than male ferns of similar age but notshiny like affinis.Notable sites Recent records from Hampdenleaf,Hatches, Angling Spring and Monkton Woods, and fromGrubbins Plantation, Little Kingshill. Older records fromthe edge of Peterley Wood and Seerhill Plantation.Ecological associates Probably the same as male fern.Derivation William Borrer was a botanist active in thefirst half of the 19th century, who apparently firstdistinguished this variety in Devon. A man of leisure, hehad a large garden and arboretum in Sussex.

Young plant of Borrer's male fern showing golden scales

Lower frond showing square-ended pinnules & lobed basal pinnule

[Golden-scaled male fern Dryopterisaffinis ssp. affinisDespite a mis-transcribed record in BMERC (amistake for Borrer's male fern), this species hasnot been found in our area. I have, however, seen itin Crowellhill Wood just to the north of our area.For distinguishing features, see under Borrer's malefern. Other subspecies of Dryopteris affinis arelimited to the north and west of Britain, and sspaffinis is also much commoner away from the south-east. It usually stands out because of its veryshaggy stalks and midribs and shiny appearance.]

Note shiny surface, rounded ends to pinnules and no lobes on basal ones

10.13Narrow buckler-fern Dryopteris carthusianaThere are records for this fern from 12 woodlands, but most ofthem are in the 1970s only. Only two sites are confirmed for the1980s and 1990s, which have survived into the current century.It likes consistently wet conditions and may well have been lostfrom most of its former sites because of the lowering of thewater-table and drier climate in the last two to three decades.Identification From the male ferns it is told by its moredissected fronds and not forming "shuttlecock" clusters; frombroad buckler fern it differs in its generally narrower frond (likemale fern), paler green colour, and scales with no dark stripe.Notable sites Still present in very wet parts of Monkton Wood,where it was recorded by Ted Byrne in 1974 (then considered"scarce") and in Peterley Wood (3 plants found by Ted Byrne in1979 and similar number present today). It still grows by twoponds on Naphill Common, just over the boundary of our area.Ecological associates As for other Dryopteris, but none notedlocally, given its rarity.

Soft shield-fern Polystichum setiferumCompared to our two main woodland ferns above, male and broad buckler, other species are decidedly uncommon inour area. The most frequent of them is the soft shield-fern, although it is restricted to just a few ancientwoodlands and hedgebanks. It tends to prefer slightly drier spots such as woodland banks.Identification The fronds are bipinnate like male fern and can grow equally tall, although in our area they areusually rather shorter. While the pinnules of male fern are broad at their base where they join the midrib, thoseof the shield-ferns are more or less stalked, giving the fern a more divided look. The pinnules also have a "thumb"-like lobe at the base and their teeth are prolonged into hair-like points.Notable sites There are records from just eight sites, of which three are woods (Cross Coppice, Sandwich Woodand Angling Spring Wood), three are ancient lanes, where it occurs on shady hedgebanks (Boss, Broombarn andGreenlands Lanes), and the last two are the grounds of Missenden Abbey and the old overgrown churchyard byGreat Missenden Parish Church. It is easily overlooked and it may well occur at further sites in the area.Galls Only one fungus gall has been recorded in this country, and that only in Shropshire.Mines The two Psychoides moths mentioned under hart's-tongue fern are also known to mine Polystichum and maywell do so in our area, although they have not been noted specifically on soft shield-fern.Other ecological associates No other species have been recorded locally on shield-ferns, although that is notsurprising given their sparsity.Derivation For the name "shield-fern" see under broad buckler fern above. "Soft" refers to the feel of theleaves and the hair-like extensions of the teeth, in distinction from hard shield-fern (below).Variation Various cultivars are on sale at garden centres and sometimes used in municipal plantings. One was seenin 2018 in a roadside verge beside Lodge Wood, adjudged (by Martin Rickard) to belong to the 'Tripinnatum group'.

Young soft shield-fern fronds showing the form of the pinnules More mature plant showing superficial similarity to male fern

10.14

Polystichum setiferum 'Tripinnatum group' with finely divided fronds (3-pinnate) and very scaly midrib, Lodge Wood

Hard shield-fern Polystichum aculeatumA very rare fern in our area with just one older record, but currently known from three sites. Druce (1926) said itwas "local and generally rare" in our area "nearly extirpated by commercial collectors". It is rather ironic that thisspecies, that was removed from the countryside into gardens is now on the course of a return journey, as at leastone of the current specimens is clearly a garden escape!Identification As the name suggests, this fern has leathery fronds that last well through the winter and feeldistinctly stiff, as do the hair-like points on the teeth of the pinnules, which are quite bristle-like. The lower edgeof the pinnule "thumb" is straight and leaves a space between it and the stalk of the pinna, easily seen when thefrond is held against the light.Notable sites It has long been known from the old churchyard behind Great Missenden Parish Church and stillsurvives there, so may be native. It also occurs nearby in the deep ditch beside Church Lane, at the boundary ofold Missenden Abbey land, plentifully on the walls of Missenden Abbey gardens, and in a nearby garden. It appearsnative on the shady banks of Greenlands Lane, Prestwood. Lastly, a fine clump occurs in a ditch at the edge ofLodge Wood. It is frequently sold in garden centres and occurs regularly in gardens.Varieties It hybridises with soft shield ferns in areas where both are frequent (P. x bicknellii). Some localspecimens so far determined as setiferum seem tougher and intermediate in pinnule characters, so the hybrid mayoccur in our area, perhaps from crossing with garden aculeatum. The crucial test is that the hybrid is completelysterile.

Hard shield fern (Great Missenden) Underside showing spore-heaps

Family: Polypodiaceae (Polypodies) 10.15

Common polypody Polypodium vulgareDespite its name this fern is decidedly uncommonlocally. There are two records from the 1970sand one from the 1990s, at none of which siteshas it been seen since, so that only one record(1982 and 2001) is recent and the species isprobably extinct in the area. The older records(1970s, 1980s) are all "sensu latu", which mayrefer to interjectum (see below), no attempthaving been made to differentiate the variousspecies of Polypodium.Identification Polypodies are distinct withsimple 1-pinnate fronds arising singly in lines froma creeping rhizome. In our area they may befound on walls or hedgebanks, but in wetterwestern areas often grow on mossy tree boughsor on the ground in sand-dunes.Notable sites Once recorded at PrestwoodParish church, but no specimens have been foundsince 2001, a victim of wall-cleaning. A clump hashowever escaped from a garden along PrestwoodHigh Street and can be seen at the base of thewall beside the gate.Ecological associates Two leaf-mining flies havebeen reported on Polypodium in this country, butneither has been noted locally.Human associations None.Derivation "Polypody" is from the Greek for"many-footed" and either refers to the frondsgrowing singly from separate bases or to theseries of rootlets along the rhizome.

Intermediate polypody Polypodium interjectumThis species grows in more calcareous areas, while common polypodyusually grows in more acid or neutral substrates. It is probably thecommonest polypody in the south-east and can be plentiful on limestonewalls in south Oxfordshire, the Cotswolds and some other parts of theChilterns. In our area, however, it is limited to just two sites.Identification There are three British species of polypody. Commonpolypody (above) has narrower fronds that are parallel-sided; southernpolypody (P. australe) has very broad fronds and only grows in the westof the country (in spite of the confusing name); while the currentspecies is intermediate in shape, widening in the middle. It is alsodistinct from vulgare in its two basic pinnae turned forwards out of theplane of the frond ("inflexed"), although this feature is somewhatvariable in both species.Notable sites Garden wall of cottage at Stonygreen, where it has beenknown for over 50 years; hedgebank outside garden in Whitefield Lane,Great Missenden, where it appears to be a recent garden escape.Varieties Common and intermediate polypodies may hybridise to formP. x mantoniae. A possible specimen was reported by Alan Showler in1989 from a grassy garden wall in Hughenden Valley. The hybrid issterile and therefore unlikely to have survived long.

[Family Salviniaceae] 10.16

[Water fern Azolla filiculoidesOur only water fern (introduced) has not so far beenrecorded in our area, but does occur in ponds in the widerChilterns, where it is usually a garden throw-out. It growsvigorously and can persist a long time. In autumn its redfronds make it highly conspicuous. It often covers thewhole surface of the water and prevents light reachingsubmerged flora and fauna.]

[Family Marsileaceae][Pillwort Pilularia globuliferaA primitive fern native to marshes on old acid commons. Never recorded in our area and very rare in the Chilternswith only one known site - Nettlebed Common (discovered in 2018 by Andy McVeigh). Submerged much of thetime, the long thin rhizomes put up very slender fronds with curled tips (more leaf-stalks than proper leaves), atthe base of which small globular fertile leaves (the "pills" of the name) develop and release spores into the mud.