This article was first published in the Newsletter of the London Natural History Society, No. 240 February 2016
Meetings planned nine months in advance cannot anticipate railway line closures but Annie, Ian, Jill, Juliet and Mario managed to survive the Rail Replacement Service to meet Rodney Burton at trainless Erith Station on a day when the temperature reached the thirties, or the 300s if you like it expressed on the Kelvin scale. The plan was to look at the flora of TQ5080.
We drove to our starting point on the Belvedere Industrial Estate, built on old grazing marsh on the south side of the Thames Estuary, most of it inaccessible. On the planted verges as we walked down Crabtree Manor Way North to the sea wall was the alien Narrow-leaved Ragwort Senecio inaequidens in full flower and the remains of Annual Beard-grass Polypogon monspeliensis, a plant of damp places by the sea and no doubt native here even if the habitat isn’t the way it used to be. The road turned into a more productive public footpath with late summer herbage, including frequent Bilbao’s Fleabane Conyza floribunda, before reaching the sea wall itself. An eight foot drop on the seaward side stopped us reaching the riverside vegetation so we had to practise distance botany.
The foreshore here has distinct zones although not all are present in all places. From top to bottom they are: brambles and other scrub, rough herbage, a masonry embankment in various states of repair, covered or not by green algae or a seaweed, Bladder Wrack Fucus vesiculosus to my untrained eye, then a zone of deep, glutinous and treacherous slime going down to the water. Sea Aster Aster tripolium was abundant along the high tide mark in its rayed form, interspersed with unrayed var. discoideus, and Sea Couch Elytrigia atherica was easily named from the path, as was Sea Plantain Plantago maritima. Common Cord-grass Spartina anglica is the only cord-grass recorded from this area so we assumed that the large mound we could see was that species, but it was frustrating not to be able to get to plants needing more detailed examination. The Tomato Solanum lycopersicon seedling in a muddy gutter was no compensation.
Fortunately the top of the embankment gradually rose as we went westward and gave access to the foreshore with some prospect of getting back again, so over I went. A single False Fox-sedge Carex otrubae, a plant that can tolerate some salinity, was hidden in the herbage and Wild Celery Apium graveolens, well past flowering, was nameable by its smell and abundant in several places.
From the path Rodney had spotted the dead stems of another umbellifer that I hadn’t noticed even though I was standing next to it: Hemlock Water-dropwort Oenanthe crocata. In the cracks between the stones of the embankment were vegetative Sea Arrowgrass Triglochin maritima and a few plants of Lesser Sea-spurrey Spergularia marina, a frequent component of the new inland salted-verge habitat.
Jill had gone ahead into the next square west and found a large and healthy clump of a polypody near the top of the embankment. All the ones I have seen in similar maritime places have been Intermediate Polypody Polypodium interjectum and so was this, confirmed micros-copically later. So it was back over the wall with the help of a large block of foam polystyrene and carrying a 4lb club hammer that I’d found at the edge of the river. How does something with the buoyancy of a club hammer come to be washed up?
We retraced our steps to go eastward along the footpath, where we found Japanese Rose Rosa rugosa on the embankment, then came across steps that made foreshore access easy for everyone. It was also a good lunch spot with somewhere to sit and a vision of scenic South Essex across the river. By the steps Common Saltmarsh-grass Puccinellia maritima grew between the stones and there were large and small patches of Sea Milkwort Glaux maritima, not in flower.
Jersey Tigers (moths, not carnivores) have become more common in the London area and we did see a couple, but they wouldn’t pose for a photograph.
We continued along the path and along the foreshore where possible, where Sea Club-rush Bolboschoenus maritimus formed swathes. On the landward side was a patch of a rhizomatous spurge, possibly Gáyer’s Spurge Euphorbia x gayeri, so named not because it’s more happy, joyful and lively than other spurges but for the Hungarian botanist Gyula Gáyer.
Just under the sea wall was a single Sea-purslane Atriplex portulacoides, to date the most westerly record on the south side of the estuary. A little further on the foreshore changed to a hundred metres of golden sandy beach, an unusual feature for the Thames. In this case it had covered the usual grey grime after being blown over from a large pile in the adjacent industrial area, on top of which Rodney, being vertically unchallenged, spotted Sheep’s Sorrel Rumex acetosella.
A derelict concrete pier looked interesting but produced only Squirreltail Fescue Vulpia bromoides and Rat’s-tail Fescue V. myuros, both well withered. We reached the edge of the square, beyond which Giant Hogweed Heracleum mantegazzianum, Weld Reseda luteola and Fern-grass Catapodium rigidum were new for the day but no good for TQ5080, although we did find Fern-grass near the cars when we got back to them.
TQ4879 had few records so we went on to visit it, starting in Veridion Way in the industrial estate. A mown bank on the south side of the road appeared to have been sown with a ‘wild’ flower mix at some time. Hedge Bedstraw Galium album was abundant but the only plant to quicken the pulse, for its intrinsic qualities rather than its external beauty, was a small and flat rosette of Corn Parsley Petroselinum segetum on barish ground. We crossed a narrow stream with another tuft of False Fox-sedge at the water’s edge and an unreachable Duckweed Lemna sp. then went into a dry, tall-grassy field, most of which was False Oat-grass Arrhenatherum elatius. Accompanying it were Red Bartsia Odontites vernus, Field Bindweed Convolvulus arvensis, fruiting Meadow Barley Hordeum secalinum, Horse-radish Armoracia rusticana, a horse, a Holly Blue and Ruddy Darters.
We had a good day with 108 species in TQ5080 and 96 in TQ4879, even if recording slowed down a bit because the staff kept stopping to eat blackberries, and thank Rodney for leading the meeting with his usual accuracy and thoroughness.