Stoneworts in Shropshire

Shropshire Botanical Society Newsletter 5 - Spring 2001 - pages 8-13

Nick Stewart & Alex Lockton

 

Stoneworts, or charophytes, are a group of complex algae that are usually included in the recording activities of botanical societies because they superficially resemble vascular plants more than they do other groups of algae. They are all rather difficult to identify and, as the taxonomy has changed somewhat in recent years, we do not accept any records without a voucher specimen. However, this can be a definite advantage, as it means anyone can make an interesting record, especially as so little is known about them in Shropshire. We have included in this account all records for the county, but only those determined by Jenny Bryant (JAB) or Nick Stewart (NFS) can be considered completely reliable in terms of modern taxonomy.

 

Chara aspera Deth ex Willd.

Rough Stonewort

National status: scarce

Extinct in Shropshire

This plant has only been recorded in Shropshire twice. William Leighton collected it at Cole Mere (SJ43) in 1840, and William Beckwith found it at Acton Burnell (SJ50) in 1882. There are specimens of both of these at the Natural History Museum. It is thought to be declining throughout England & Wales.

Chara aspera

 

Chara contraria A. Braun ex Kutz

Opposite Stonewort

National status: scarce

Rare in Shropshire

Although it is only occasional in south-east and central England, this species is widespread elsewhere. It sometimes occurs in deep waters, but more usually in shallows at the edge of lakes or in pools that dry up during summer. It has been recorded in the Shrewsbury Canal at Upton Magna (SJ51, 1881, J. Groves); at Shawbury Heath (SJ52, 1881, W.E. Beckwith); and at Dolgoch Quarry (SJ22, 1998, S.J. Whild det. NFS). One of the specimens from the latter site was determined to be the variety Chara contraria var. hispidula.

 

Chara contraria

Chara globularis Thuill

Fragile Stonewort

National status: frequent

Not rare in Shropshire

Early records for this species, up to 1924, could just as easily be C. virgata, which was considered first a variety, then a subspecies, of C. globularis, but is now fully recognised as a separate species.

C. globularis sensu lato was first recorded at Berrington Pool (SJ50) by Leighton in 1836, and was later seen in the same place by James Groves in 1881. It was found in Wellington Reservoir (SJ61) by Edward Forrest in 1890, and again by William Hunt Painter in 1900. The precise location of the reservoir eludes us - possibly the pool by the Ercall, or possibly the ones by Dothill, to the north of Wellington. George Claridge Druce also recorded it at Bomere Pool (SJ40/50) in 1908.

Records for C. globularis sensu stricto date from 1983, when Marjorie Wainwright collected it (det. JAB) at Quina Brook (SJ53) and Stokesay Castle (SO48). It was found in various places along the Montgomery Canal (SJ32, 1997-'98, R.V. Lansdown, det. NFS) and most recently by Julie Edwards (det. NFS), who collected it from ponds at Aychley Farm (SJ63) in 1998.

 

Chara globularis

Chara hispida L.

Bristly Stonewort

National status: occasional

Extinct in Shropshire

There are old records for this species by Edward Williams at Kynnersley on the Weald Moors (SJ61) in about 1800, and by Augustin Ley at Whittington (SJ33) in 1882, but it has not been seen in the county since then.

Chara hispida

 

Chara rudis (A. Braun) Leonh.

Rugged stonewort

National status: rare

Extinct in Shropshire

This was apparently recorded in Rushbury Station Yard (SO59) in 1880, but we don't know who the recorder was. It was subsequently recorded at Crose Mere (SJ43, 1884, H.F. Parsons) and Bomere Pool (SJ40/50, 1908, G.C. Druce). It is possible that some old (pre 1920s) records for Chara globularis could actually be for this species.

Chara rudis

 

Chara virgata Kutz.

Delicate Stonewort

National status: frequent

Not rare in Shropshire

The first record is from Berrington Pool (SJ50), where it was collected and recorded as C. aspera in 1832 by Rev. John Stevens Henslow but a specimen at the Royal Albert Memorial Museum in Exeter was recently redetermined as this taxon by NFS.

There are subsequent collections from Berrington Pool dated 1834 (probably Henslow again) and 1881 (J. Groves). Norman Hicken found it in the Dowles Brook (SO77) in 1965 (det. S.P. Phillips), and it has been found to be frequent in the Montgomery Canal (SJ32 & SJ33, 1997-'98, R.V. Lansdown det. NFS). In 1998 it turned up in Dolgoch Quarry (SJ22), in the same pool as the Chara contraria and in a pool at a factory in Telford (SJ61); and in 1999 at Haughmond Hill (SJ51) (all of these coll. S.J. Whild det. NFS).

 

Chara virgata

 

Chara vulgaris L.

Common Stonewort

National status: frequent

Not rare in Shropshire

Although this species is called Common Stonewort, it is not necessarily any more common than some of the others, and should certainly not be recorded without proper determination of a voucher specimen any more than the other taxa should. Edward Williams described it as "common in ponds and ditches" in about 1800, but we don't really know to which species he was referring. Augustin Ley had the first confirmed record for the county in 1882 (det. H. & J. Groves) but he did not record the locality. This was probably the same record that was published without date, recorder or locality in the Journal of Botany in 1883.

 

Chara vulgaris

The first real Shropshire record was therefore as late as 1899, when William Hunt Painter collected it at Hem Mill (SJ70, det. H. & J. Groves), although the general confusion surrounding this species was added to by this being published as "Shifnal" in the Victoria County History of 1908. In 1902 Painter also claimed to have found it at Rushbury Station Yard (SO59), but there is no independent confirmation of his identification, and one has to wonder if it might not have been C. rudis (although they can grow together). Painter also claimed to have it at Tickwood (SJ60, 1903). We can only hope these specimens turn up in a herbarium some day.

Apart from this short burst of recording at the turn of the century, there are no records for Common Stonewort until 1985, when Mary Scruby collected it in a "pool near Cronkhill Farm" (SJ50, det. JAB) during a survey for the National Trust. The grid reference shows this to have been a pool within the grounds of Berrington Hall, and on the opposite side of the road from Cronkhill Farm, so there is possibly some confusion here. Marjorie Wainwright found it in a pool at New Hall Farm at the foot of Wenlock Edge (SO49, 1986, det. JAB) and in a flush on the edge of Sweeny Fen (SJ22, 1999, det. NFS). Kate Thorne also collected this species on Titterstone Clee (SO57, 1999, det. NFS).

There are various recognised varieties of Chara vulgaris. The var. longibracteata was collected from the Mere at Ellesmere (SJ43) by William Beckwith in 1882 (det. NFS). Var. papillata was apparently also collected by Beckwith in 1883 (det. H. & J. Groves) but the location is unknown; and was subsequently found by Ian Trueman in the old Shropshire Canal at Coalport (SJ60, 1981, det. JAB).

 

Nitella flexilis agg.

Smooth Stonewort

There are now thought to be two species - Nitella opaca and N. flexilis. N. opaca, Dark Stonewort, is dioecious (having male and female reproductive organs on different plants) whereas N. flexilis is monoecious. Unfortunately, when no reproductive organs are present, it is impossible to say which species you have. Under these circumstances, the aggregate N. flexilis agg. is recorded. This must also be used for all old records without voucher specimens, as the two taxa have been confused in the past.

The oldest records for Shropshire are by Edward Williams, who recorded it at Berrington Pool (SJ50), White Mere (SJ43), Betton Pool (SJ50), Bomere Pool (SJ40/50), Hencott Pool (SJ41), Shrawardine Pool (SJ31) and Eaton Mascott pool (SJ50). William Leighton collected it near Holly Coppice on Haughmond Hill (SJ51, 1839); Henry & James Groves found

Nitella flexilis agg.

 

it in the Shrewsbury Canal (SJ51, 1881); and William Hunt Painter found it at Ratlinghope Common (SO49, 1897) - where it was still present in the Threshold Pools in 1999 (A.K. Thorne, det. NFS). Elsewhere on the Long Mynd, there is one from 1985 at Round Hill (SO49, Mary Scruby, det. JAB), and one from New Pool Hollow (SO49, S.J. Whild det. NFS).

During the Shropshire Flora project Bryan Fowler collected N. flexilis agg. in the Moat at Cheswardine (SJ72, 1977) and in a stream at Woore (SJ74, 1978) (both det. JAB). Marjorie Wainwright collected it at Eyton upon the Weald Moors (SJ61, 1982) and in the Montgomery Canal at Queen's Head (SJ32, 1983) (both det. JAB).

Two other sites have been recorded as having N. flexilis agg: Weston Lullingfields (SJ42, 1999, P. Parker det. NFS) and Brown Moss (SJ53, 1999, S.J. Whild det. NFS).

 

Nitella flexilis (L.) Adargh

Smooth Stonewort

National status: occasional

Not rare in Shropshire

The only place in Shropshire where N. flexilis sensu stricto has been recorded is the Montgomery Canal, where Richard Lansdown found it in almost every 1km length of the Shropshire parts of the canal (SJ33, SJ32, SJ22, 1997, det. NFS).

Nitella flexilis

 

Nitella opaca N.F. Stewart

Dark Stonewort

National status: frequent

Not rare in Shropshire

Because this taxon has been distinguished at various points in the past, there are some old records for it, but how reliable these are we do not know. The first Shropshire one is from the Journal of Botany in 1880, but the site is not given. In 1908 George Claridge Druce found it at Bomere Pool (SJ40/50).

In 1999 it turned up in Wildmoor Pool (SO49, S.J. Whild) and at Ashes Hollow (SO49, A.K. Thorne) (both det. NFS), and it seems likely that it could account for all the records of the aggregate on the Long Mynd. It was also found in a temporary pool in grassland near Craig Sychtyn (SJ22, S.J. Whild, det. NFS).

 

Nitella opaca

Nitella gracilis (Smith) Agardh

Slender Stonewort

National status: vulnerable

Extinct in Shropshire

This is one of the great mysteries of Shropshire botany. It has been found only once, among some specimens of Potamogeton collected by W.E. Beckwith and sent to Arthur Bennett. Beckwith always refused to name the locality and would only describe it as "a small deep pool, about 1/12th acre in extent, Shropshire". The specimen is at the Natural History Museum, and has been confirmed by all the leading experts. It may have been on the Long Mynd, possibly Wildmoor Pool, because all of Beckwith's other records that year were from around Church Stretton. But we may never know for sure. N. gracilis is the rarest species of charophyte recorded in Shropshire - it is considered a Red Data Book species in Britain and Ireland, although it is widespread in the northern hemisphere.

 

Nitella mucronata var. gracillima J. Groves & Bullock-Webster

Pointed Stonewort

National status: scarce

Rare in Shropshire

This is known only in the Montgomery Canal (SJ32), where it was found to be quite widespread during a survey in 1997 & 1998 (coll. Whild, Lansdown & Lockton det. NFS).

 

Nitella mucronata var gracillima

 

Nitella translucens (Persoon) Agardh

Translucent Stonewort

National status: occasional

Extinct in Shropshire

This has only been recorded twice: once in 1856, by an unknown recorder, at Shawbury Heath (SJ52, det. Groves & Groves) and once at Tong Castle (SJ70) by William Hunt Painter in 1897.

Nitella translucens

 

Discussion

As the species accounts demonstrate, there are only a few records of charophytes in Shropshire. They occur typically in more calcareous water bodies, but it is worth looking for them just about anywhere that there is standing water - even just temporary pools in farmland. George Claridge Druce famously described one species as a "vegetable comet" - arising in huge quantities one year and then completely disappearing for several years thereafter. At Dolgoch Quarry the quantity that formed in a temporary pool one year was so enormous that when it dried up the skeletons of the dessicated stoneworts lay an inch deep on the ground.

The only effective method of recording charophytes is to collect a specimen if you happen to come across one. They will keep fresh in a pastic bag for a day or two - long enough to bring it to the county recorder. Alternatively, vouchers can be made by carefully floating out the specimen in a sink full of water, and allowing it to settle on a sheet of thin white card. It will stick there firmly, so make sure it is arranged in such a way as to make examination easy.

This makes them ideal subjects for Botanical Society members to record. You need no identification skills beyond the ability to recognise that the plant in question is a stonewort. By all means have a go at identifying it, but properly determined specimens are essential. Always label every specimen with the date, collector and site.

Please send all specimens in the first instance to Sarah Whild, who will forward them to Nick Stewart for determination, if appropriate. Happy hunting!

 

Further reading

Moore, J.A. 1986. Charophytes of Great Britain & Ireland. BSBI Handbook No 5. Botanical Society of the British Isles, London.

Stewart, N.F. & Church, J.M. 1992. Red Data Book of Britain & Ireland: Stoneworts. Joint Nature Conservation Committee, Peterborough.

Stewart, N.F. 1996. Stoneworts - Connoisseurs of Clean Water. British Wildlife 8:92-99.

 

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