Elytrigia repens (L) Desv. ex Nevski subsp. arenosa (Spenner) A. Love

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Sujfolk Natural History, Vol. 31

ELYTRIGIA

REPENS

ARENOSA

(L.) DESV. EX-NEVSKI SUBSP. (SPENNER) A. L Ă– V E P. J. O. TRIST

This grass has no English name and is a subspecies of Elytrigia repens, Common couch grass, which has a distinct habitat on the sea shore. It has had little recognition in Britain and its first appearance in a British Flora was in Stace (1991). It was first recognised by Koch and Ziz (1814) on the Mainz sands in Germany. No more was heard of it until Holmberg (1926) reported it from Denmark, Finland and Sweden. Later, in 1933, it was reported by Jansen and Wächter from the Netherlands. In more recent years it has been studied by Korneck (1966) and Hecker (1987) on the Mainz sands. The late Dr. Hubbard knew of it from near The Wash in 1936 and, with the late Eric Swann, he collected plants at Burnham Overy Staithe, Norfolk in 1967.

In 1972 I was corresponding with the late Dr. Hubbard on Agropyron (Elytrigia) when he told me he had specimens and living plants of Triticum repens var., maritimum Koch & Ziz (an earlier illegitimate name for subsp. arenosa) which had been sent to him from the type locality near Mainz. At this time the grass was not on our British lists but I was aware that Hubbard intended to pursue his early observations. However, his health intervened, but he told me that this taxon needed investigation and that he proposed to pass on his specimens from Germany to Dr. Melderis. Melderis never saw these specimens, but from earlier exchanges with Hubbard he was able to describe this subspecies in Flora Europaea (1980).

The quest for subsp. arenosa in Britain Following this publication I enquired of Dr. Melderis for information on the British localities. He told me that its inclusion in Flora Europaea (1980) was simply on the authority of Dr. Hubbard. The Melderis description was brief and I needed to see a specimen before starting field work. At Kew I was able to see Hubbard's specimens from Germany and I took detail of the characters differing from subsp. repens (Common couch). Subsequently at the British Museum 1 handled many sheets of Agropyron repens but found no evidence of annotation by Melderis referring to subsp. arenosa, but I did find two specimens which I identified as subsp. arenosa. At the Herbarium of Leicester University there were two sheets labelled Agropyron repens var. maritimum Koch & Ziz which had been determined by the late Professor Tutin and these specimens were similar to those which I had identified at the British Museum.

The next move was to the field. My first living plants were seen on fixed dunes at L'Ancresse Common, Guernsey. Later I set out for the Suffolk coast and located plants at Walberswick, Dunwich, Sizewell and Thorpeness. In the following year I collected from two sites on the Normandy coast east of Caen.

All specimens from these areas matched those I had seen at Kew and I was satisfied that this taxon could be included in the British lists.

A detailed survey of subsp. arenosa around the coast of Britain has not been carried out. On the east coast of England it has been located in east and west Norfolk, east Suffolk, and south Essex. It has also been found in west Sussex and south Somerset. From Guernsey and north France there are recent records.

Trans. Sujfolk Nat. Soc. 31 (1995)

ELYTRIG1A

REPENS SSP.

ARENOSA

55

Habitat The habitat of subsp. arenosa is distinct and may be considered as a diagnostic feature. It is found on sand at beach level, on low dunes and on high dunes at the rear of beaches. It is sometimes within 30 m of the tide but is more often found at about 70 m. It has a resistance to overspills of sea water, but this would rapidly drain through the sand. Some plants shortly to be mentioned indicate a slight build up of sodium chloride. The fact that this plant is sometimes in close proximity to the tide and its saline influence, only infers some salt tolerance.

The pH of the Suffolk sands ränge from six to seven. If you cross the car park and go over the bridge on the marsh at Walberswick, you can find subsp. arenosa. On your left towards the sea, look for clumps of the Common couch together with Glaux maritima, Atriplex portulacoides and Spergularia marina.

At Thorpeness it grows with Ononis repens and Silene uniflora in coarse sand and small stones. I found O. repens was also associated with Ammophila arenaria and Tamarix gallica on mobile fine sand at the rear of beaches in Normandy. At Dunwich there were a few plants in small pockets of sand between large shingle at the back of the sea defences in Company with Lathyrus japonicus. The Guernsey site was colonised with grasses and herbs and the subsp. arenosa plants were small, Single culmed and widely spaced. In one small area our plant was within the good Company of French oat-grass Gaudinia fragilis. Ă–n the Mainz sands in Germany, subsp. arenosa remains in its natural habitat in spite of the fact that this area is c. 400 km from the coast, while it is mainly recorded from maritime sands around the coasts of north west Europe. The inland sandy stations in Germany suggest that this taxon requires open sand habitats rather than specifically maritime ones. It may be surmised that this particular subspecies now in its maritime stations has been deprived of its former inland sand habitats by gradual erosion over time and has taken refuge on the sand areas that remain on the coast. In spite of many fruitless searches I still hope to find this plant in Breckland.

Description of subsp. arenosa Elytrigia repens subsp. arenosa is a smaller plant than subsp. repens. It is a perennial with rhizomes and usually forms patches, but is sometimes seen as a Single culmed plant. The length of the spikes, spikelets, glumes and the leaves are all shorter than in subsp. repens. For a field recognition, it is a couch grass with a short spike of less than 10 spikelets and all of the plant is a distinct glaucous-green. The uppermost stem leaf is considerably shorter than in Common couch and is thick and rigid with in-turned margins and broad white veins on the upper surface. In the common subspecies, the leaf is Hat with many narrow veins. Subsp. arenosa is frequently awned on both glumes and lemmas but confusion should be avoided with E. repens var. aristatum which has awned lemmas up to 15 mm long. In our plant subsp. arenosa lemma awns are 0.3-2.8 mm long and are thick and rigid but are sometimes replaced by a strong mucronate tip. Glume awns are rarely found on Common couch and in subsp. arenosa an awn of 1.0-2.3 mm may be found.

Trans. Suffolk Nat. Soc. 31 (1995)

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Suffolk Natural History, Vol. 31

Distribution It has been found in north Spain, The Netherlands, Finland, Sweden and Germany. With the exception of the inland sites in Germany, all other records are from coastal martime sands.

The E. Suffolk field records are found in Sujfolk Natural History, 29: 40 (1993).

References Hecker, U. (1987). Agropyron maritimum in Die Farn-und Blutenpflanzen des Mainzer Sandes. Mainz Naturw. Arch., 25: 85. Mainz.

Jansen, P. & Wächter, W. H. (1933). Triticum maritimum Koch & Ziz in Grassen Längs De Zuiderzeekust 111. Nederl. Kruidk. Arch., 43: 178.

Holmberg. O. R. (1926). Agropyron repens var. maritimum Koch & Ziz in Scandinavian Flora 2: 274. Stockholm.

Koch, W. D. J . & Ziz, J. B. (1814). Triticum repens var. maritimum in Cat. pl.

Palat., 5: 17. Mainz.

Korneck, D. (1966). Agropyron repens var. maritimum in Wiederfund von Kochia arenaria Roth im Naturschutzgebeit 'Mainzer Sand'. Hessische Floristische Briefe, 178: 49.

Melderis, A. (1980). Elymus repens subsp. arenosus in Tutin, T.G. et al., eds.

Flora Europaea 5: 196. Cambridge.

Stace, C. A. (1991). Elytrigia repens (L.) Desv. ex Nevski subsp. arenosa (Spenner) A. Löve in New Flora of the British Isles, 1066. Cambridge.

P. J. O. Trist, Glovers, 28 High Street, Balsham, Cambridge CB1 6DJ

Trans. Suffolk Nat. Soc. 31 (1995)

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