Berkshire: River Thames Cholsey-Wallingford

21 August 2013                                     OS Map 175 Reading/Windsor

All day

We parked in Ferry Lane. Cholsey SU599857 and walked down the lane to the River Thames.  At this juncture is Cholsey Marsh Nature Reserve (BBOWT).  This is fenced off for breeding snipe, but the constituent plants can be seen from the lane and the subsequent footpath.  The plants here can also be seen along the bank of the Thames going north to Wallingford (most of the day was on the Thames Path trail).  The appendix lists all the marsh and waterside plants we saw during the morning.  Compared with many other sections of the Thames this stretch is still rich in plantlife.  Our only real disappointment was not seeing any greater dodder Cuscuta europaea at its classic location along this river.  Although we have seen it elsewhere we have yet to find it beside the Thames.  Dragonflies were naturally much in evidence, although many were too strong-flying for us to get a chance to identify them.  We did record common darter, small red damselfly, and banded demoiselle.

Cholsey Marsh with reed canary-grass, great willowherb and meadowsweet

Common comfrey

Orange balsam and great willowherb

Marsh woundwort

Amphibious bistort

Gall of gall-midge Wachtliella persicariae on amphibious bistort

Brown sedge in Cholsey Marsh

Reed sweet-grass with reed canary-grass in front

Pfeiffer's amber snail on hedge bindweed leaf

Hedge bindweed was clambering over most of the tall vegetation

Gipsywort

Bean galls of sawfly Pontania proxima on crack willow

Common fleabane

Mine of moth Stigmella salicis in osier leaf

Bittersweet

Gall on meadowsweet caused by fungus Triphragmium ulmariae

Common skullcap

Hard rush inflorescence; its narrow stiff grey stems distinguish it from  soft rush

Purple loosestrife

Confused Michaelmas-daisy has colonised much of the riverbank

Viviparous form of cocksfoot grass, quite common late in the season

Tufted vetch

Branched bur-reed

The river itself supported few aquatics, given the continuous boat traffic.  Away from the bank, these plants were mainly limited to yellow water-lily, unbranched bur-reed and spiked water-milfoil.  Close to the bank but still in the water were common club-rush, yellow iris, branched bur-reed, bulrush, great water dock and water-plantain.

Thames near Cholsey

Yellow water-lily and its "brandy-bottle" fruits

Great water dock

Unbranched bur-reed

Common club-rush

Some way north of Cholsey Marsh, opposite the village of North Stoke, were a couple of pasture fields which, although now dry, had obviously been wet earlier in the year, especially in shallow hollows.  The Berks Flora indicates that the Red Data Book grass-poly Lythrum hyssopifolium had been seen in this area.  Once considered extinct in the county, it was rediscovered in 2001 and seen again in 2002.  Despite an extensive search we did not unfortunately see any, although our expectations were low for this plant, which is an annual and does not necessarily appear every year.

Shortly after this we passed a boathouse and a wooden platform at the bank of the Thames where there was a quiet pool which had flowering rush, yellow loosestrife and greater duckweed - all of which may have been introductions, as we saw them at no other spot.  Here we also saw the river snail Viviparus viviparus.

Great and common duckweeds

River snail

Flowering rush

After walking under the main road bridge we were on the outskirts of Wallingford, passing the ends of large gardens, before housing began to extend close to the river.  Here hops were common draped over fences and bushes.  A stream branched off west, where we saw a group of poplar fieldcap Agrocybe cylindracea toadstools growing at the base of a large willow.  We took the footpath beside this stream up to the road which we followed north to The Partridge for an excellent lunch in the back garden under the shade of a tree, relaxing with a glass of rosé.

Hop leaf with mine of fly Agromyza flaviceps

Poplar fieldcap on willow trunk

 

After lunch we took the chance to explore a back street just west of the main one, as we continued north to the centre of town.  Here there were plenty of urban and wall specialists to keep us occupied - Guernsey and Canadian fleabanes Conyza sumatrensis & canadensis, pellitory by the wall Parietaria judaica, tall rocket Sisymbrium altissimum, Oxford ragwort Senecio squalidus, ivy-leaved toadflax Cymbalaria muralis, wall barley Hordeum murinum, water bent Polypogon viridis, wall lettuce Mycelis muralis, nipplewort Lapsana communis, green alkanet Pentaglottis sempervirens, sun spurge Euphorbia helioscopa, yellow corydalis Pseudofumaria lutea, rough mallow Malva neglecta, hollyhock Alcea rosea, biting stonecrop Sedum acre, Mexican fleabane Erigeron karvinskianus, and creeping bellflower Campanula rapunculoides - a considerable haul in just half a kilometre!

Water bent with annual meadow-grass and field forgetmenot

Creeping bellflower

Mexican fleabane and pellitory of the wall by Wallingford Bridge

From the centre of Wallingford we continued north by the footpath beside the Thames.  Here we passed many of the morning's waterside plants, although not quite so rich.  We added crow garlic to our list.  After a kilometre we decided to turn back, past the bridge and along Thames Street in Wallingford to where the footpath begins again beside the river going south.  This section, which we had earlier omitted by leaving for the south end of Wallingford, was much affected by the proximity of the town and had little more to offer, although we did see a single plant of arrowhead in the river.  We continued south along the path we had walked in the morning, checking once more fruitlessly for greater dodder.  We saw just a single plant of Indian balsam Impatiens glandulifera, so we presumed that this aggressive alien was regularly rooted out whenever it appeared.

 Appendix: List of marshland and water plants

Alder Alnus glutinosa (frequent)
Angelica, wild Angelica sylvestris (frequent)
Arrowhead Sagittaria sagittifolia (once)
Balsam, Indian Impatiens glandulifera (once)
Balsam, orange Impatiens capensis (frequent)
Bindweed, hedge Calystegia sepium (abundant)
Bistort, amphibious Persicaria amphibia (occasional)
Bittersweet Solanum dulcamara (occasional)
Bulrush Typha latifolia (occasional)
Bur-reed, branched Sparganium erectum (frequent)
Bur-reed, unbranched Sparganium emersum (abundant)
Canary-grass, reed Phalaris arundinacea (abundant)
Chickweed, water Myosoton aquaticum (once)
Chicory Cichorium intybus (once)
Club-rush, common Schoenoplectus lacustris (occasional)
Comfrey, common Symphytum officinale (frequent)
Comfrey, Russian Symphytum x uplandicum (occasional)
Cranesbill, meadow Geranium pratense (occasional)
Dewberry Rubus caesius (abundant)
Dock, great water Rumex hydrolapathum (occasional)
Duckweed, greater Spirodela polyrhiza (once)
Figwort, water Scrophularia aquatica (occasional)
Fleabane, common Pulicaria dysenterica (frequent)
Garlic, crow Allium vineale (occasional)
Gipsywort Lycopus europaeus (frequent)
Hop Humulus lupulus (occasional)
Horsetail, water Equisetum fluviatile (once)
Iris, yellow Iris pseudacorus (frequent)
Loosestrife, purple Lythrum salicaria (frequent)
Loosestrife, yellow Lysimachia vulgaris (once)
Meadow-rue Thalictrum flavum (occasional)
Meadowsweet Filipendula ulmaria (frequent)
Michaelmas-daisy, confused Aster novi-belgii (frequent)
Mint, water Mentha aquatica (frequent)
Osier Salix viminalis (frequent)
Reed Phragmites australis (frequent)
Rush, flowering Butomus umbellatus (once)
Rush, hard Juncus inflexus (occasional)
Sedge, brown Carex disticha (occasional)
Sedge, false fox Carex otrubae (occasional)
Sedge, great pond Carex riparia (frequent)
Sedge, hairy Carex hirta (occasional)
Sedge, lesser pond Carex acutiflorus (frequent)
Sedge, pendulous Carex pendula (occasional)
Sedge, remote Carex remota (occasional)
Sedge, slender tufted Carex acuta (frequent)
Sedge, spiked Carex spicata (occasional)
Silverweed Potentilla anserina (frequent)
Skullcap, common Scutellaria galericulata (occasional)
Sneezewort Achillea ptarmica (occasional)
StJohn's-wort, square-stalked Hypericum tetrapterum (occasional)
Sweet-grass, reed Glyceria maxima (abundant)
Vetch, tufted Vicia cracca (occasional)
Water-lily, yellow Nuphar lutea (frequent)
Water-milfoil, spiked Myriophyllum spicatum (occasional)
Water-plantain, common Alisma plantago-aquatica (occasional)
Waterweed, Nuttall's Elodea nuttallii (once)
Willow, crack Salix fragilis (frequent)
Willow, white Salix alba (occasional)
Willowherb, great Epilobium hirsutum (abundant)
Woundwort, marsh Stachys palustris (frequent)