First of all, I must recommend the following website, which I have used extensively for identifying many difficult plants - www.naturespot.org.uk.
(All photos taken at OPS.)
Total number of species (all genuses) reported at OPS = 814 (285 Plants, 150 Insects, 130 Animals, 249 Birds (inc. escapes)).
Jump to Water Plants Jump to Trees & Shrubs Jump to Shore Plants
Jump to Ferns, Mosses, Algae and Lichens Jump to Grasses Jump to Fungi
Bittersweet (aka Woody Nightshade)
Bulbous Foxtail - identified in WWT survey within 1km (nationally scarce)
Canadian Fleabane by jetty. Tiny white/yellow flowers
Chicory in the wildflower meadow next to car park
Coltsfoot large leaves, where weather tower used to be
Common Broomrape. A parasite of clover.
Common Dog-violet (white version in wood by orchard)
Common Eyebright very pretty small plant, on path of Lagoon 3, at SW end.
Common Ragwort common yellow plant around the lagoons
Common Spotted Orchid - lip divided into three equal lobes and marked with dark pink dashes and broken lines. (Leaves - not shown - spotted.)
Dog Violet (inc. white-flowered)
Early Marsh Orchid
Giant Hogweed not on site currently
Goldilock's Buttercup in woods
Grape Hyacinth garden escape on seawall at Shepperdine
Greater Knapweed paints the meadow next to the car park purple in late summer !
Gypsywort bank of lake, next to road (where dogs go in lake). Like mint, but with no smell.
Hemp Agrimony Large patches on Lagoon 2
Hoary Willowherb - WWT survey, Lagoon 3, 2019
Ladys Bedstraw common on the path round Lagoon 3
Meadow Thistle very common (note smooth stems)
Montbretia has been escaping from gardens for about 100 years ! Below are the berries. The familiar flowers are also bright orange.
Musk Mallow, usally pink flowers but also this white form.
Opium Poppy garden escape, Lagoon 2
Perennial Sow-thistle on the saltmarsh by the jetty, late summer
Perforate St John's-wort along tarmacd path to Lagoon 2
Red Bartsia low-lying but distinctive, along the paths round Lagoon 2
Sand Crocus - on stony area of Lagoon 2, near pond.
Scentless Mayweed Lagoon 3, by the stone pile
Sea Clover - identified in WWT survey within 1km (nationally scarce). At top of the seawall, by Lagoons 1/2.
Sea Radish - along shore, especially by the jetty
Smooth Cats Ear
Southern Marsh Orchid - rounded side lobes and a small toothlike central lobe; marked with darker dots and dashes. (Leaves - not shown - usually unspotted.)
Spear-leaved Orache - along shore, especially by the jetty
Spotted Medick black spots in the centre of clover-like leaves. On Lagoon paths.
Sun Spurge around the jetty fence
Sweet Violet (white form) near orchard.
Tall Melilot common on path of Lagoon 2
Travellers Joy (aka Old Mans Beard)
Thrift (or Sea Pink) a few clumps on the sea-wall by Lagoon 2
Upright Hedge Parsley
Water Mint Lagoon 2
Wild Carrot the white flowerheads have a single purple flower in the middle (cultivated carrots belong to a different subspecies).
Wild Parsnip - Lagoon 2
Bogbean - in shallow pond by visitor centre
Fools Watercress in the rhines (or on the banks after the farmers dredging !)
Lesser Reedmace - in shallow pond by visitor centre
Spiked Water Milfoil
Aspen shimmers in wind. Tall specimens along main rhine, by entrance. Round, toothed leaves.
Black Hawthorn Two trees in hedge between shore and Lagoon 3.
Black Poplar quite large, heart-shaped leaves. Tall, thin trees.
Common Whitebeam - identified in WWT survey, 2019.
Cotoneaster (C. franchetti), Franchet's Cotoneaster. Single plant at north end of Lagoon 2 (red-orange berries in Sept). Non-native, garden escape, spread by birds eating the berries. (Note that many Cotoneaster, e.g. C. horizontalis, but NOT this one, cause problems to native plants by spreading and are illegal to plant in wild (i.e. added to Sched 9 of Wildlife & Countryside Act in 2010).)
Crack Willow the hedge across Lagoon 1 shows Crack Willow (yellowy branches, green leaves, on left) and White Willow (green branches, darker green and longer leaves with white backs, on right)
Eared Willow - identified in WWT survey, 2019.
Elm a good specimen is along the bridleway at far end of lake, which runs along the SW side of Lagoon 3. On left of path (over ditch), the first tree in the tall hedge just before path zig-zags.
Field Maple distinguished from Sycamore by sides of fruit being in a straight line. Large example on far side of main rhine, just down from entrance.
Grey Willow - identified in WWT survey, 2019.
Hornbeam - 4 specimens in hedge that runs from road along SW side of Lagoon 3.
Horse Chestnut - just one small tree growing through brambles on Lagoon 2.
Oak (Pendunculate Oak)
Osier (Willow) - identified in WWT survey, 2019.
Scots Pine all the pine trees on-site are this species.
Sea Buckthorn the large silvery bush on the seawall of Lagoon 1
Sloe (aka Blackthorn) white flowers before leaves appear, early Spring
Spindle pink fruit in late autumn. Specimen along tarmacd path to Lagoon 2, near old visitor centre
Sweet Chestnut the only specimen is on the lawn in front of the Gatehouse/old Visitor Centre
Turkey Oak nice specimen on right of approach road. Acorns have hairy base.
Wayfaring Tree shrub with red and black berries, Lagoon 2
White Poplar large specimen at SW end of Lagoon 3. White back to grey leaves.
White Willow see photo under Crack Willow, above.
Wild Cherry heavy fruiting tree by the entrance (flowers in April)
Wych Elm note the unsymmetrical leaves at the stalk end this identifies Elms. Nearly all the hedge on the left side of the tarmacd path from car park to Lagoon 2 contains Wych Elm, especially at the end by the pond.
Yew there are only two specimens on-site, both on Lagoon 2. Largest at South end, next to path.
Biting Stonecrop at top of seawall by Lagoon 1
Bladder Wrack commonest black seaweed along the shore
Common Cord Grass binds soft silt mud together at exposed side of salt-marsh
Marram Grass Taller, grey-green grass, on the land-side of saltmarsh.
The photo below is of the saltmarsh at Shepperdine, showing the two above grasses (with more commoner grasses on the seawall).
Sea Aster common succulent plant on saltmarsh with purple and yellow daisy-like flowers
Sea Milkwort on the seawall
Common Scurvygrass succulent plant on saltmarsh with white flowers starting in May.
I can highly recommend the following website for identifying grasses - www.naturespot.org.uk.
Barren Brome by jetty.
Cock's-foot common along Severn Way sea-wall.
Common Couch - WWT survey Lagoon 3, 2019.
Common Reed the reeds in the large beds on Lagoons 2 & 3
Common Soft-brome common along Severn Way sea-wall.
Creeping Soft-grass common along Severn Way sea-wall.
False Fox Sedge
Greater Pond-sedge in pond to south of Lagoon 3.
Long-bracted Sedge - WWT survey Lagoon 3, 2019.
Pampas-grass 2 clumps in middle of Lagoon 3.
Pendulous Sedge one large clump at south end of Lagoon 2.
Perennial Rye-grass common along Severn Way sea-wall.
Reflexed Saltmarsh-grass common along Severn Way sea-wall.
Sea Couch - WWT survey Lagoon 3, 2019.
Sharp Rush - WWT survey Lagoon 3, 2019.
Tall Fescue Lagoon 3, at top of entrance ramp.
Yorkshire-fog common along Severn Way sea-wall.
Crimson Wax Cap
Dog Vomit Slime Mold
Dung Fungus orange
Scarlet Elf Cap
St. George's Mushroom
Spectacular Rustgill Mushroom not edible
Taphrina alni (Alder Tongue)
Velvet Shank on stumps in mid-winter
No. of species = 285