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Suffolk Natural History, Vol. 41
A wild giant horsetail hybrid hunt In early July 2004 I joined Chris Preston from National BRC and Trevor James from Plantlife on a hunt for some elusive hybrid horsetails referred to in Simpson’s Flora of Suffolk. Trevor had recently (Dines & Bonner, 2002) described a new hybrid horsetail, E. × robertsii from Anglesey. He had referred to the Suffolk records in his paper and was keen to see if they could be re-located. Like many of Francis’ records cited in the Flora, there was not much detail to go on and no herbarium specimens to support the records. The two records of ‘Equisetum × dubium’ (an incorrect name for E. arvense × telmateia) are: ’24, edge of a shady marsh at Foxhall, an old-established colony’ and ’40, Belton, 1977’. We had a good idea where the first site was and, after a short while searching around the footpath alongside the stream near Foxhall Stadium, we were able to find a colony of Field Horsetail (E. arvense) which showed white stems between the nodes like that of Giant Horsetail (E. telmateia). Trevor was able to confirm that they were in fact a variant of E. arvense and did not show hybrid characters from telmateia. We then went on to Wickham Market to look for E. × willmotii. This time we had a little more detail to go on; Simpson has: ‘Equisetum fluviatile × telmateia This interesting hybrid extends over an area of marshy ground and on the banks of the R. Deben near Glevering Mill, Wickham Market. The area was formerly a shallow lake in the Deben watercourse. Observed in this habitat in 1928 but not then identified. Detd. E. L. Swann, 1972.’ I was able locate a record card made by Eric Swann with a grid reference for this site and we called at Glevering Mill with high hopes. The owner was most helpful and gave us free access to search the grounds; we showed him the record and he pointed out that, as the ground was so boggy and overgrown with large nettle beds, the best way to reach the area was by boat. A small rowing boat was lying, half submerged, in the old mill stream and with some effort it was raised from the deep and cleaned. After much hunting a hot water bottle stopper was procured to seal the drainage hole and we were ready to embark. Chris and Trevor were very dubious as to whether the craft was seaworthy and decided to brave the swamp on foot leaving me to navigate upstream with one paddle whilst standing in the prow! The stream was very overgrown with tall bulrushes, masses of Yellow Water Lily and clumps of River Water Dropwort, Oenanthe fluviatilis - a rare plant in Suffolk. After paddling for a few hundred metres I reached a bend in the mill stream where there were several plants of a tall horsetail growing amongst reeds (Phragmites) standing in water about a metre deep. They were impossible to reach from the land and I was glad the boat stayed dry long enough to collect a few specimens for Trevor. Although these plants were bigger than typical E. fluviatile and again showed rather white stems, they did not have characters of telmateia and were definitely not hybrids. We pressed on up to Belton to hunt for the second record of E. arvense × telmateia and visited a number of likely spots including Belton Fen before arriving at the caravan park at Howard’s Common. Within a few yards of the
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car park we came across more plants of E. arvense with the same whitish stems that we had seen at Foxhall. Again, Trevor was confident that these were not hybrids but odd forms of arvense. We are confident that all three records of hybrids with E. telmateia in Simpson (1982) are the result of confusion with plants of arvense and fluviatile with whitish stems. Colonies of Equisetum are very long-lived and although we cannot be certain that the populations we found were in fact the same as those recorded in the Flora, it is very likely that they were. References Dines, T. D. & Bonner, I. R. (2002). A new hybrid horsetail, Equisetum arvense × E. telmateia (E. × robertsii) in Britain. Watsonia 24: 145–157. Simpson, F. W. (1982). Equisetum in, Simpson’s Flora of Suffolk, p. 77. Suffolk Naturalists’ Society, Ipswich. Martin Sanford SBRC, Ipswich Museum, High Street, Ipswich IP1 3QH
Trans. Suffolk Nat. Soc. 41 (2005)