Grimwith Reservoir

Saturday 16^th July 2022

Leader: Bruce Brown

Today’s field meeting was a joint trip with the Wild Flower Society with a total attendance of 18. It was a beautiful summers day, perfect weather for botanising as the peak of the heat wave hadn’t yet arrived. We began by investigating the pretty grassy margins of the car park where there was quite a diversity of flowering plants including Common Spotted-orchid (Dactylorhiza fuchsii), Common Twayblade (Neottia ovata), Eyebright (Euphrasia sp.) and Fairy Flax (Linum catharticum). More Common Twayblade was found in good numbers below a Downy Birch (Betula pubescens) and near by were Flea Sedge (Carex pulicaris), Common Yellow-Sedge (Carex demissa), Autumn Hawkbit (Scorzoneroides autumnalis) and Wall Speedwell (Veronica arvensis). A good start and we hadn’t even left the car park!

We made our way leisurely eastwards on a track, turning left onto a path nearer the reservoir where Shore Horsetail (Equisetum x litorale) was growing abundantly. Bruce explained how to identify this hybrid between Water Horsetail and Field Horsetail. A little further along, I was pleased to find Marsh Willowherb (Epilobium palustre), a plant I’m not familiar with. The plant has a club shaped stigma and the flowers typically droop downwards. Passing through some moorland, our path was unusually lined with the lime green flowers of Soft Lady's-mantle (Alchemilla mollis) and we wondered how this garden plant had got here. Some of the Heather (Calluna vulgaris) had started to flower already.

Our small path joined back onto the main track and Jesse soon pointed out a plant of Northern Dock (Rumex longifolius). Jesse explained the differences between Northern Dock, Broad-leaved Dock (Rumex obtusifolius) and the hybrid between these two species, Rumex x hybridus which were all growing in close proximity. Nearby were some more plants we don’t see too often, White Sedge (Carex canescens), Pale Sedge (Carex pallescens) and Bristle Club-rush (Isolepis setacea). We ate our picnic overlooking the reservoir with the restored 400 year old cruck barn of Grimwith High Laithe just behind us.

One of my highlights of the day came soon after lunch, as nestled in the grassy margins of the track was Adder's-tongue (Ophioglossum vulgatum). This is an unusual looking fern which, although frequent throughout most of the British Isles, is hard to spot among the grass and is probably often overlooked. Bruce said the grass here is kept relatively short, and therefore to the liking of the Adder’s-tongue, by grazing geese, although the grass was getting a little too long in places. We found quite a number of Adder’s-tongue although only a few with the fertile frond developing. Further along we came across a group of Northern Marsh-orchid (Dactylorhiza purpurella) but the flowers were well past their best. Later finds included a good stand of Brown Sedge (Carex disticha) and, beside the track, a small amount of Meadow Barley (Hordeum secalinum). A wet ditch gave us Tufted Forget-me-not (Myosotis laxa), Fen Bedstraw (Galium uliginosum) and Knotted Pearlwort (Sagina nodosa). Too many interesting species to keep up with!

We then headed over to the draw-down zone of the reservoir, the mud still very wet in places, so we had to watch our step. Here were yet more species that we don’t encounter very often such as Mudwort (Limosella aquatica), Water-purslane (Lythrum portula), Marsh Arrowgrass (Triglochin palustris) and the pretty Marsh Speedwell (Veronica scutellata) and Marsh Cinquefoil (Comarum palustre). Marsh Pennywort (Hydrocotyle vulgaris) and Water-pepper (Persicaria hydropiper) were frequent here as well as the ubiquitous and invasive New Zealand Pigmyweed (Crassula helmsii). Another plant of note was a subspecies of Greater Plantain (Plantago major ssp. intermedia), the leaves with only 3 obvious veins. We then returned to the cars, partly retracing our steps, noting a few more species for the list including Greater Burnet-saxifrage (Pimpinella major) and Ivy-leaved Crowfoot (Ranunculus hederaceus).

Text by Susan

Photographs by Susan, Tom and Brigid