By Bert Reid
|Many of you will have noticed white edges along our
motorways and major roads during April and May. This
ribbon of white along the verges and central reservations
is caused by the flowers of Cochleria danica (Danish
Scurvygrass). This is a seaside plant which was first
noted in Worcestershire in 1977, on railway ballast at
the edge of a saline pit at Stoke Works. During the
period of the Flora Project (1987 to date) we have seen a
dramatic increase along the main road system where salt
is used in winter and now the distribution map of the
plant can double up as a major road atlas.
Cochleria danica Danish Scurvygrass (right)
Cochleria danica is a very easy plant to see and record. Not many plants can be confidently recorded while driving at 70 mph along the motorways. Even non-botanists will notice it and ask about it.
|Less well known are some other plants that have also
spread along salted roads in a similar fashion. Puccinellia
distans (Reflexed Saltmarsh-grass) is just another
grass to most people. The only chance we have to record
this on motorways is to wait for the traffic jams - it is
a plant for the pedestrian rather than the motorist. Spergularia
marina (Lesser Sea-spurrey) is a bit easier because
it has little pink flowers, but it is a very low- growing
plant and small patches can easily be overlooked, even on
foot. The fourth seaside plant along some main roads is Plantago
coronopus (Buck's-horn Plantain). This is a fairly
widespread native on the sands around Kidderminster, but
outside this area is strongly associated with bare road
verges. It is definitely not a motorist's plant. Another
seaside plant we have recorded is Atriplex littoralis (Grass-leaved
Orache) but this only has a couple of records, both from
the M5 motorway.
Puccinellia distans Reflexed saltmarsh grass. (left)
The best chance to find these seaside plants is to walk along the verges of major roads. On the 17th June 2001, the Flora Project organised a field meeting to Evesham. Included in the area covered was a section of the A46T Evesham bypass. Cochleria danica was first noticed on the bypass in 1996 and was known to be quite widespread along the road by the time of the field meeting, but no other saline plants had been recorded. Bill Thompson soon pointed out Puccinellia distans by the road, and we also managed to find small patches of Spergularia marina and Plantago coronopus. To the best of my knowledge, none of these 3 species had been previously recorded from the hectad.
|Spergularia marina Lesser Sea-spurrey (below)
Plantago coronopus Buck's-horn Plantain (below)
Catapodium marinum Sea Fern-grass (above)
|During the meeting we only covered a small section of
the bypass, which goes through ten 1 km. squares to the
south and east of Evesham. I decided that it was
important to investigate the road more thoroughly, so
over a few days I donned the gas mask and earplugs and
walked the road. I kept strictly to the road edges (both
sides) and fixed my gaze to the narrow strip of the edge.
I now have a permanent stoop and glazed eyes but the
recording was very successful. I found Cochleria
danica in seven of the ten monads, Puccinellia
distans in nine, Spergularia marina in eight and Plantago
coronopus in four.
On the 29th June I was walking along the south-western end of the bypass when I spotted a vaguely familiar grass. It was a small, stiff, bright green grass with tight one-sided flower spikes. At last the penny dropped and I remembered what it was and where I had seen it. It was Catapodium marinum (Sea Fern-grass) and I had seen it before on some of my rare trips to the seaside. There were seven good clumps of the grass - a first record for the county. The second county record came two days later when I spotted four very tiny plants on another part of the bypass.
Where did these seaside plants originate? The obvious answer would seem to be introduction with the de-icing salt now used so widely on our main roads, but there is good evidence that this is wrong. The spread of halophytic plants on road verges is one of the most remarkable recent changes in the British flora. The phenomenon was first reported in 1976 by Matthews & Davidson from north-eastern England and further articles by Scott & Davidson (1982) and Scott (1985) give a clear picture of the early years of the spread. The first successful coloniser was Puccinellia distans and the history of its spread shows quite clearly that the earliest records were close to the coast with a subsequent linear expansion inland. A similar picture can be seen with Spergularia marina. Cochleria danica was a late starter with few records before the late 1980s but has made up for lost time with a remarkable expansion, again starting with roads near the coast.
This history strongly suggests a natural expansion from "traditional" coastal sites. Human activity has created a series of continuous corridors of suitable habitat along the bare, salt-burned verges of major roads, and vehicular slipstreams and the carriage of mud by cars and lorries has assisted seed dispersal. Anyone who has walked the edges of major roads will be well aware of the powerful suction force created by fast travelling vehicles, especially large lorries.
What will come next? The most successful colonisers are all plants of the edges of saltmarshes, usually on rather bare compacted soil, and all have light seeds, which spread easily. We are already seeing a few cases of spread onto more minor roads in parallel with the increased use of de-icing salt and this trend is likely to continue. A number of other saline plants have been seen on road verges in other parts of the country, and some of these may well reach Worcestershire if they are not already here unrecorded. The most likely candidates in my opinion are Cochleria officinalis (Common Scurvygrass), Puccinellia maritima (Common Saltmarsh-grass), Hordeum marinum (Sea Barley) and Parapholis strigosa (Hard Grass). These are all well worth looking out for, and if anyone finds them before me I won't be too upset!
Another seaside plant that we have found on roadsides a few times is Armeria maritime (Thrift). This plant has clearly spread from deliberate planting in gardens etc. and is also found on the Evesham by-pass with other ornamental planting in the centre of a roundabout. The Evesham plants have not managed to colonise the verge yet, but I would not be surprised to see them spreading in future.
A final surprise from the Evesham by-pass turned up on 26th August. On the demolished foundations of what was probably a barn in an arable field just off the by-pass I found two species of Sea-lavender. One was Limonium latifolia, the Florists' Sea-lavender and the other was an as yet unidentified relation of Limonium sinuatum with winged stems but unlobed leaves. Both are clearly relics of cultivation for use as dried flowers in flower arranging. 200 metres away, on the very edge of the road and growing with Puccinellia distans and Spergularia marina, were three or four plants of the unidentified Limonium.
So forget long trips to Bournemouth, Brighton or Blackpool. For the best seaside plant hunting just come to Evesham and stroll along the by-pass!
|MATHEWS, P & DAVISON, A.W. (1976). Maritime species on roadside verges. Watsonia, 11: 164.|
|SCOTT, N.E. & DAVISON, A.W. (1982). De-icing salt and the invasion of road verges by maritime plants. Watsonia 14: 41-52.|
|SCOTT, N.E. (1985). The updated distribution of maritime species on British roadsides. Watsonia, 15: 381-386.|
The following maps show the current distribution of some halophytic plants as revealed by the current Worcestershire Flora Project. The first coincidence map shows the distribution of all the species and provides a road map of the county!
Reflexed saltmarsh grass is found on semi-bare mud, round estuaries, the upper edges of saltmarshes, inland saline areas, and along salted main roads.
Lesser sea-spurrey is found in sandy or muddy maritime areas, at inland saline places. Locally frequent inland.
Buck's-horn plantain is a native British plant which grows on barish ground or amongst very short turf on gravelly or sandy soils, mostly near the sea. The map above shows that it is quite frequent on the sandy soils in the Kidderminster area, and infrequent elsewhere.
Danish scurveygrass is common on many sites near the sea, and on salt-treated roads inland.
The map caption comments are derived from STACE C 1997 New Flora of the British Isles. 2nd edition. Cambridge University Press.
The following extract was written by Fred Fincher (Trans. Worcs. Nats Club 1952, Vol 10, part 4, pages 265-269: Worcestershire has long been noted for its maritime plants and the earliest record appears to be Glyceria maritima (now Pucinellia maritima) Common Saltmarsh grass in1796 near the Droitwich Canal. Most were solitary records, and the plants never established themselves, but several are well-established and still maintain their hold. On the Keuper Marl the main area of interest is at Droitwich where brine has been known and worked since Roman times. A few plants have been recorded near Tewkesbury. Here, before Longdon and Welland Marshes were drained and various locks and weirs constructed, the Severn was tidal to well above Tewkesbury and the low-lying ground would have been inundated with saline water during floods.... He then lists the plants with comments. Many have now vanished since 1952: our current best saltmarsh has developed at Upton Warren. All very different from the modern roadside invaders.
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