Saturday, 17 May 2014

Hay meadow treasures

This morning I took a group from Rutland Natural History Society on a walk round a couple of hotspots in the Nene Valley. We started at Castor Station, where we looked at the riverside vegetation, enjoyed seeing plenty of Banded Demoiselles (it's going to be a bumper year for this species), found a freshly emerged Scarce Chaser and spent some time looking at  various fish and invertebrates that Pete had collected from the river, including some baby Spined Loach.

The botanical highlights came in the second part of the morning, when we visited part of Castor Flood Meadows SSSI which is owned by the Nene Park Trust. This unimproved hay-field proved to be a real gem, with all the species that you might expect - Sanguisorba officinalis, Silene flos-cuculi, Filipendula vulgaris, Ophiuoglossum vulgatum, Silaum silaus, Carex disticha - the list could go on.

However, there were three star species. On the slightly drier ground at the western end there was a good population of Meadow Saxifrage Saxifraga granulata, at one of its very few Peterborough sites.  It is now more frequent in churchyards and cemeteries than in old meadows. In the dampest part of the field we found two areas of Tubular Water-dropwort Oenanthe fistulosa, a much declined species which is now classified as Vulnerable in the UK RedList.

Saxifraga granulata

I was also delighted to see that the population of Early Marsh-orchid Dactylorhiza incarnata was still present (having last surveyed it over 10 years ago) and seems to be having a good year. Pete counted at least 100 spikes before he gave up. A number of the spikes were the classic pale flesh-pink of D.incarnata subsp. incarnata, but a much larger proportion were a deep pink, and key out to D. incarnata subsp. pulchella, which is supposed to occur on more acid soils, although it can occasionally occur in neutral marshes and fens, and recently has been found as a coloniser of fly-ash tips in the Lee Valley, Hertfordshire. Stace considers that the majority of the subspecies of D.incarnata would be better considered as varieties - so who knows?

Dactylorhiza incarnata subsp. incarnata

Dactylorhiza incarnata subsp. pulchella

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