Berkshire/Oxfordshire: Godstow and Port Meadow

18 July 2016                   OS Landranger 164 Oxford

Half day

We parked in the car-park of The Trout at Godstow, as we planned to eat there on our return, it being open all day, which relieved any time pressure. 

We walked over the road bridge (wall-rue Asplenium ruta-muraria and pellitory-of-the-wall Parietaria judaica) to the path to the ruins of Godstow Nunnery or Abbey, built originally in the 1130s out of local limestone on what was then an island in the Thames.  Following dissolution in 1539, it became a private house and farm, but was ruined in the course of the Civil War, since when just these rather plain outline walls remain. 

Godstow Nunnery

On, and at the base of, the walls were pellitory-of-the-wall, fern grass Catapodium rigidum, common (mostly) and Oxford ragworts Senecio jacobaea and S. squalidus, white stonecrop Sedum album, long-headed poppy Papaver dubium, round-leaved cranesbill Geranium rotundifolium (sticky with dense long glandular hairs all over), thyme-leaved sandwort Arenaria serpyllifolia, black horehound Ballota nigra and good king henry Chenopodium bonus-henricus. 

Round-leaved cranesbill, thyme-leaved sandwort and fern-grass

Black horehound & Good King Henry

Pellitory-of-the-wall

The grassland is rough but not remarkable, having musk thistle Carduus nutans, burnet-saxifrage Pimpinella saxifraga, lady's bedstraw Galium verum and hoary plantain Plantago media.  A dry ditch going west from the ruins, mostly occupied by a hedge, however, is the most renowned site for the rare alien birthwort Aristolochia clematitis, scrambling stems with heart-shaped leaves and strange narrow yellow trumpet flowers.  There was much of it for a short stretch, but does not seem to have spread far, given that it has been here for centuries, introduced it is said by the nuns for its medicinal properties, supposed to assist childbirth, but its toxicity perhaps indicates a more covert use for abortions. 

Birthwort

Between the ruins and the Thames to the east is a large white poplar Populus alba. 

White poplar

We walked south from here along the west bank of the Thames, surprised to see two posts in the river each surmounted by a resting common tern.  Swallows were swooping over the water.  After passing through a lock we were again in rough meadow, with yellow rattle Rhinanthus minor and infrequent pyramidal orchid Anacamptis pyramidalis and woolly thistle Cirsium eriophorum. 

Woolly thistle

Musk thistle

Much more vegetated were the banks of the Thames with meadowsweet Filipendula ulmaria, gypsywort Lycopus europaeus, water figwort Scrophularis aquatica, purple loosestrife Lythrum salicaria, great willowherb Epilobium hirsutum, marsh woundwort Stachys palustris, hemlock water dropwort Oenanthe crocata, water forgetmenot Myosotis scorpioides, water mint Mentha aquatica, wood horsetail Equisetum sylvaticum and common club-rush Schoenoplectus palustris. 

Marsh woundwort

Meadowsweet and purple loosestrife

 We only saw a little Indian balsam Impatiens glandulifera, presumably indicating regular efforts at control.  Some of the trees at the bank were black poplar Populus nigra hybrids and one very large old specimen had conspicuous leaf galls caused by the fungus Taphrina populina, with yellowish bulges above and bright yellow hollows beneath. 

Hybrid black poplar and fan

Galls of Taphrina populina on hybrid black poplar

There was little aquatic vegetation because of frequent boat traffic, although there were large flocks of greylag geese with occasional domestic hybrids (regularly chased from the banks into the water by dogs, much to the birds' annoyance), the odd Canada goose, frequent mute swans and a heron flying by. 

Greylag and domestic geese

A pair of pied wagtails were calling in a riverside bush and goldfinches liked the rough meadow.  Dragonflies in evidence were the banded agrion Calopteryx splendens and common blue damselfly Enallagma cyathigerum. 

Common blue damselfly

Other regular aerial traffic were Globemaster troop-carrier planes from nearby Brize Norton.  The shells of swollen river mussel Unio tumidus were common in shallow water edges. 

Globemaster

Swollen river mussel

Near Binsey we passed chicory Cichorium intybus, lucerne Medicago sativa and fly honeysuckle Lonicera xylosteum. 

Chicory

Fly honeysuckle

At Medley Weir to get to Port Meadow we crossed two bridges, as the Thames is here split into two streams. 

Thames and Port Meadow from Medley Weir

Instead of going straight across Port Meadow, we walked south along the Castle Mill Stream which is free of boat traffic and by far the best place for water plants, which included amphibious bistort Persicaria amphibia, Canadian pondweed Elodea canadensis, yellow water-lily Nuphar lutea, great and creeping yellow-cress Rorippa amphibia and R. sylvestris, brooklime Veronica beccabunga, pink water-speedwell V. catenata, marsh cudweed Gnaphalium uliginosum, and reed sweet-grass Glyceria maxima. 

Amphibious bistort Creeping yellow-cress

Pink water-speedwell Great yellow-cress

Undisturbed by the flocks of geese, this was also a harbour for smaller birds like the mallard and moorhen.  At the southern end of Port Meadow we left the stream and walked across to the concrete path that takes one some way north on the east side.  Port Meadow was being grazed by sizable herds of both horses and cows, while a large part was still under water from the river flooding its banks earlier in the year. 

The shallow lake attracted a large flock of mature and juvenile black-headed gulls, accompanied by a pair of little egrets.  Overhead flew red kites.  In the event, our path along the east side was halted by deep water half way along and we had to return to the south side and proceed up the west side, not far from the Thames, which provided the only dry route to the north end.  While on the east side, however, we recorded water-plantain Alisma plantago-aquatica, tubular water-dropwort Oenanthe fistulosa, hard rush Juncus inflexus, slender spike-rush Eleocharis uniglumis (usually a coastal species), fool's watercress Apium nodiflorum and fan-leaved water-crowfoot Ranunculus circinatus.  We were surprised to see a single plant of flowering rush Butomus umbellatus in bud, a species we had not seen here on previous visits. 

Tubular water-dropwort

Flowering rush

At the marshy edge of the lake below the embankment along which the path ran we were also pleased to find several plants of creeping marshwort Apium repens, the rare highlight of this site, noticeable at first by the slightly differently-shaped leaflets from fool's watercress, but confirmed by many bracts at the base of the flower umbel, which was long-stalked, and the creeping stems rooting at each node.

Creeping marshwort

Tiny black rove-beetles with prominent eyes proved to be the common wetland species Stenus juno.  At the north end of Port Meadow we could exit through the car-park at Wolvercote and complete the round trip by walking a few hundred yards west to the Trout.