2003 East London 6th and 7th September Main Meeting
Advocates of urban botany were in for a real treat on John Swindells' excellently prepared and well-run meeting.
The canals of East London were set up to service the great port of London back in the early 1800s. They were the motorways of their day and as such gathered a host of strange and exotic plants, some of which remain to this day. We set off from Mile End and were soon into a bafflement of Bidens. B. frondosa, (beggarticks) B. connata (London bur-marigold) were present in addition to the more normal B. tripartita (trifid bur-marigold) and it is easy to conflate them all. A good eye will distinguish the leaf features - non-too convincingly for poor eyes we suspect. Luckily the ripe achenes beget a better naming. Those of B. tripartita are angled and flattened, with two of the angles continuing as long bristles possessing downward pointing barbs. The achene body also has downward pointing barbs. B. frondosa is similar, but the barbs on the achene body point upwards. B. connata has four bristles and is exceptionally warty between the ridges of the achene body. We all became used to working them out. Next on the confusion register were a trio of grasses where someone had been feeding the birds. Setaria pumila (yellow bristle-grass) keyed out. Phalaris canariensis (canary grass) was going over, while emergent Panicum miliaceum (common millet) completed the set. Near Salmon Lane Lock we came across that rapidly spreading alien Senecio inaequidens (narrow-leaved ragwort). Nearby was Sorbaria kirilowii (Chinese sorbaria) identified by the styles arising from well below the apex of the carpels.
The Limehouse Cut provided a wealth of new records. Angelica archangelica(garden angelica) is surprisingly common in London, which is more than can be said for Solarium chenopodioides (tall nightshade). Chenopodium ambrosioides (Mexican tea) is also well naturalised around these waterways - it smells horribly of paint or petrol. Actually in the water was that increasing invader Hydrocotyle ranunculoides(floating pennywort). We dipped in the Lee Navigation for Egeria dens a (large- flowered waterweed) which we later found actually in flower. Another local speciality hereabouts, Vallisneria spiralis (tapegrass) was also flowering in the Hertford Union Canal. Then, at Bow Wharf we found much Sisymbrium irio (London rocket) dried to a crisp, but just one or two still blooming for our visit. A good end to the first day saw us walking back to Mile End along Grove Road where Persicaria capitata (pink- headed knotweed) was all over the steps of number 34.
Day two saw us in Docklands at the Mudchute. All that spoil from digging out the Millwall Docks had to be put somewhere, as did over a century of dredging. The place is now a local nature reserve and city farm. Trifolium fragiferum (strawberry clover) was standing up to the drought pretty well. The plant's fruiting heads are said to resemble a wild strawberry. There were great stands of Euphorbia x pseudovirgata(twiggy spurge) and seeding Rumex cristatus (Greek dock) to get us all going. Then we found much Medicago sativa ssp. varia (sand lucerne) together with both its parents ssp. sativa (lucerne) and ssp. falcata (sickle medick). These three are all now at sub-species rank and are best distinguished by their seedpods. Sickle medick's are just that, sickle shaped. It is a very yellow plant with a round-headed inflorescence. Lucerne by contrast has a well wound seedpod: a bit like a snail shell. It is blue flowered. Sand lucerne is a hybrid of the two. Its seed pods are more or less intermediate as one might guess. It often shows both yellow and blue flowers on the same plant. The colour range is from a dusty yellow to almost black. One needs to look at fruit quite carefully to distinguish this last from sickle medick since back- crosses are by no means unusual. John had them all sorted out and showed us typical specimens as we all took lunch. Many other plants were seen, including Securigera varia (crown vetch), Salvia verticillata (whorled clary) andLapsana communis ssp. intermedia, (the large-flowered sub-species of nipplewort) among those still flowering despite the hot dry summer.
We walked out through Millwall Park to see Amaranthus retroflexus (common amaranth) Chenopodium bonus-henricus (good King Henry) and Ipomoea purpurea(common morning glory) which had germinated in the hot summer sun and was flowering beautifully.
Finally we wended our way to the East India Dock Basin, just across the Thames from the Dome (remember the Dome?). This is now part of the Lee Valley Park complex and boasts an emergent saltmarsh. There in plenty was Cotula coronopifolia (buttonweed) flowering alongside Aster tripolium (sea aster) in its rayed form. A real curiosity was a good stand of viviparous Elytrigia atherica (sea couch). Glaux maritima (sea milkwort) was a first for Middlesex when it turned up here and Schoenoplectus tabernaemontani (grey clubrush) had only one previous record in this locale – by Doody (c 1700) "in a pond of breach a little beyond Limehouse."
All in all we had a wonderful weekend with natives that survive and aliens that thrive in these most urban of settings.
Footnote
We found a small Euphorbia growing as a weed in pots with fan palms at Limehouse Basin. It was thought by Rodney Burton to look like Euphorbia prostrata. It has been subsequently confirmed as Euphorbia prostrata Alton by Eric Clement who has advised that it is a first British record.
BILL AND CAROL HAWKINS