Maritime plants on Suffolk's roadsides

MARITIME PLANTS ON SUFFOLK'S

ROADSIDES

E . M . HYDE

A walk along the verge of the AI 1 at Barton Mills is a hazardous experience, but it has its botanical rewards! It was in the Chalk Hill cutting in April 1980 that I first became aware that a maritime plant was beginning to colonize Suffolk's trunk roads. Covering the verge of the south-bound carriageway and the edge of the central reservation for about 350 yards was a dense mass of Cochlearia danica (Danish Scurvy-grass). This small annual, a member of the Cabbage family, is a familiar constituent of our coastal flora from Felixstowe to Benacre, but not, until then, of our main roads. The following April I found a similar colony on the A12 at Martlesham on the Woodbridge By-pass. Since then, many more colonies of this and other maritime species have been found on Suffolk roads, as indeed they have all down the eastern side of Britain.

It is the salting and gritting of the roads in winter that has enabled them to gain a foothold. Regulär applications of sah suppress the natural Vegetation on the verge, leaving patches more or less denuded of all but a few resilient plants. Passing vehicles splash further doses of salt on to the verge and a suitable habitat for maritime plants is created.

In the last few years Scott and Davison (1982) and Scott (1985) have traced the spread of these species along the roads of Britain, found similar reports from other Northern European countries, and identified the most likely source of these plants. They have established that the most successful invader is a grass, the perennial Puccinellia distans (Reflexed Saltmarsh Grass). It is now present on many miles of roadside from the Scottish border to just north of London, chiefly on the AI and Ml and roads which intersect them. P. distans is also found at many sites in Norfolk and Kent. Strangely enough, very little has been found on roadsides in Suffolk, though it is common enough in its usual habitat on the landward edge of saltmarshes. Moreover, it is so often seen in bare, man-made habitats such as quaysides (in Ipswich Docks, for example), boatyards and sea walls that it must surely soon follow C. danica on to the roads.

Salt spray affects the verges for about a yard inwards from the carriageway, though the extent varies from year to year. At Martlesham in some years C. danica occupies not only the verge but also the bank behind it. On a central reservation the colonies from the two sides frequently meet in the middle. At Trimley St Martin on the A45, for example, several yards of the central reservation have, on more than one occasion, been covered with a carpet of its white flowers. But it is at its most spectacular at Bury St Edmunds on the elevated section of the A45 where there is neither verge nor central reservation. Here, in early spring, C. danica flowers in a long white line in the dust beneath the crash barriers, beside and down the middle of the road.

How did maritime plants get on to roadsides in the first place? Scott and Davison (1982) found little evidence of any spread from inland salt-mines, although predominantly maritime plants do exist in such areas. The fact that Trans. Suffolk Nat. Soc. 22

MARITIME PLANTS ON S U F F O L K ' S R O A D S I D E S

SUFFOLK

WATSONIAN VICE-COUNTIES

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25 Eni SuliÂŤk 26 ÂŤ n l Sottolk

most populations of C. danica occur on roads emanating from the coast, and on roads connected with them leads to the conclusion that they originated from coastal sites with vehicular access. Seed is then swept along in the slipstreams of vehicles and on vehicles themselves. This could certainly be true of C. danica on the A45 in Suffolk. In 1985 I was able to trace it, apart from Ipswich itself, from just outside Felixstowe (where there are coastal sites) to the Cambridgeshire border and beyond, though there is an unexpected 5 mile gap near Beyton. Links between the A45 and the A12 could have given rise to the second site at Martlesham where the A1093 joins the A12. South-west of Ipswich it re-appears on the A12 at Capel St Mary and Stratford St Mary, and then merges with abundant populations in Essex, at least as far as Chelmsford.

The original Barton Mills record on the A l l appeared to me to be an isolated one, but it is easy to be misled into believing that the first site one discovers really is the first. It now seems more likely to have been an offshoot from the A45, though I found none in that area until 1982, two years later, despite careful searching.

Six maritime species have been recorded on our roads. More, recorded already in other counties, are surely awaiting discovery.

Trans. Suffolk Nat. Soc. 22

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Suffolk Natural History, Vol. 22

Sites of Maritime Plants on Suffolk Roadsides, 1985 Cochlearia danica L., Danish Scurvy-grass.

See distribution map. An early-flowering annual species, common on the coast. It germinates early - by January 14th in 1986.

First inland roadside record, 27.4.1980. All records (EMH), except at Stratford St Mary (G. Kitchener).

A list of all sites will be sent to Suffolk Biological Records Centre.

Spergularia marina (L.) Griseb., Lesser Sea-spurrey.

An annual, frequent in saltmarshes.

A12, Martlesham, c. 10 plants on verge at top of hill, 62/255484, 3.11.1985 (EMH).

A45, opposite Warren Heath just outside Ipswich, about 20 plants at intervals on verge, 62/203420-208420, 27.10.1985 (EMH).

Atriplex littoralis L., Grass-leaved Orache.

An annual plant, common in the drier parts of saltmarshes and on sea embankments.

A45, Ipswich, roadside verge almost opposite the new Sainsbury's stรถre, a few plants, 62/196425, 27.10.1985 (EMH).

Armeria maritima (Mill.) Willd., Thrift.

A perennial plant common in saltmarshes.

A12, Stratford St Mary, one plant on central reservation, 62/052347, 10.9.1983 (G. Kitchener). Not seen in 1985.

Puccinellia distans (L.) Pari., Reflexed Saltmarsh Grass.

A perennial grass, common on dry margins of saltmarshes and other coastal habitats.

A12, Martlesham, a few plants on verge, 62/255482,14.5.1982 (N. E. Scott).

A12, Stratford St Mary, on central reservation, 62/052347, 10.9.1983 (G. Kitchener).

A45, just outside Ipswich, many plants on verge for about 30 yards, 62/ 204422, 27.10.1985 (EMH).

A45, Woolpit, one patch on central reservation, 52/985625,1982 (EMH).

Parapholis strigosa (Dum.) C. E. Hubbard, Sea Hard-grass.

An annual grass common on the margins of saltmarshes and on tracks near the sea.

A12, Martlesham, one patch on verge, 62/255482,1983 (EMH).

I should like to thank Mr N. E. Scott for much helpful correspondence since 1980, and for Coming to visit two of our Suffolk verges in 1982. Thanks are also due to Mr G. Kitchener, who supplied our only non-coastal record for Thrift.

References Scott, N. E. & Davison, A. W. (1982). De-icing salt and the invasion of road verges by maritime plants. Watsonia 14,41.

Trans. Suffolk Nat. Soc. 22

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Scott, N. E. (1985). The updated distribution of maritime species on British roadsides. Watsonia 15, 381.

E. M. Hyde, Parkside, Wool verstone, Ipswich IP9 1AR

Trans. Suffolk Nat. Soc. 22