Llanelli Naturalists Newsletter - Autumn 1982
Richard Pryce
The Marsh Pea (Lathyrus palustris) continues to flourish and appears to be still on the increase. Some important developments have occurred at the reserve this season. Probably most significant was the clearing-out of one of the boundary ditches in July. The purpose was to recreate an area of open water principally to encourage two rare plants: Frogbit (Hydrocharis morsus-ranae) and Floating Club-rush (Scirpus fluitans) but in addition fauna such as dragonflies, amphibians and wildfowl should increase. The society was fortunate in securing a grant from the Nature Conservancy Council to cover half the cost of the hire of the excavator. Already the Frogbit is coming back and a close watch will be maintained over the next couple of years to monitor recolonisation by other species.
Another important event was the interest shown in the Marsh Pea by Dr. Jack Ellis of University College, London, who phoned me up one afternoon to ask if he could visit the fen. Then he arrived he was excited to see such a large and concentrated population of the species and collected some immature flower buds for chromosome study. Whilst in the car I casually mentioned that there was a small population of the American variety (var. pilosus) of the Pea growing on Towyn Burrows. He was even more excited at this as he had been trying to secure its seeds from America for the last ten years without success, so I took him to see the plants. Again he collected a few immature flower buds.
A few weeks later he phoned again with the results of the chromosome counts. It was apparent that the var. pilosus was diploid with a count of 14 and, that the British native was hexaploid with a count of 42. This of course means that the American variety is the ancestral form and that the British plant may have arisen from it. It is still a mystery as to how the American variety got to Towyn Burrows, probably by migratory birds, but it is the only extant population in Britain as far as I am aware.
Dr. Ellis paid a second visit last month to collect some seed for cultivation in the University garden to provide material for further study. It was interesting to note that at Ffrwd Fen the pods produced by the plant were not very fertile and only had a few seeds in each; those that did have seeds were largely eaten by maggots. On Towyn Burrows we could find no pods of the American variety, it would appear that something had stripped the plants - perhaps pigeons?
He will be revisiting both sites next year to continue his studies.
