Few water weeds can survive in the main current of the river. One that does is the Stream Water Crowfoot (Ranunculus). In May and June its massed white flowers appear above the water, often accompanied by fan-shaped tufts of aerial leaves, above the submerged mats of dark-green, thread-like leaves. It prefers places where the flow is broken by riffles and there are superb displays by the footbridge at Chilton Foliat and by the road bridge in Hungerford. Masses of this plant are a sign of health, not only for the young trout that shelter and feed among the trailing mats but for the myriad food-webs of insects, snails and other water life that live among it.
Most other water plants require quieter reaches. However, there are plants that live midstream, although they are not very conspicuous. One is the 'frog-spawn alga', a brownish, slimy weed that clings to large stones and is common in late spring. Closely examined, it does indeed look like miniature frog-spawn, and is a beautiful sight under the microscope. Another primitive alga is Hildenbrandtia, which forms thin reddish crusts on submerged flints that look like fragments of brick. Much less attractive is the brown scum sometimes seen on the surface, made of countless microscopic diatoms which normally live on the bottom, but float upwards on sunny days on bubbles of oxygen they produce during photosynthesis.
The shallow but fast-flowing backwaters of the river are the ideal place to find watercress, which likes clean, well-oxygenated water. The Kennet and its inflow streams used to support cress-beds at Ramsbury and Axford. If you gather watercress, make sure you don't confuse it with an aquatic umbellifer, which often grows with it. This is Lesser Water-parsnip, which has similar but lighter green and toothed leaves, while its frothy white flowers give the game away in late summer. A submerged, all-green plant in many of the backwaters is Water Starwort, so called because of its radiant terminal leaves. There are several British species which are very hard to tell apart. Ours is the Blunt-fruited Water Starwort, which prefers chalk streams.
It is on the water margins and the grassy flood-plain beyond, that we find the greatest variety of flowers. Among the earliest, is the lovely Marsh Marigold lining the ditches of the former water meadows.
Above: Marsh Marigold
In late spring, some meadows are yellow with buttercups; while nearer the water will be tussocks of purple, lilac and white flowered Comfrey. June is the month of greatest variety, with pink Campion and Ragged Robin, blue Forget-Me-Nots and Speedwells, and Yellow Flag Iris. In midsummer, you can hunt for orchids, first the Early Marsh, with pink flower spikes, followed by the purple Southern Marsh and the pale, lilac-splashed Common Spotted.
Above: Purple Loostrife
Late summer is marked by the pinks and purples of Purple Loosestrife, Marsh Woundwort and Hemp Agrimony, the white-flowered, jagged-leaved Gipsywort, and the pretty deep-yellow flowers of Common Fleabane. Many water meadows still have the grid of ditches used to water the fields in winter to ensure an early 'bite' of grass for sheep. These are often lined with Pond Sedge, Lady's Smock, Marsh Valerian and other marsh plants. You can tell a 'wild' meadow from a cultivated one by counting the grasses. Wild meadows will have more than a dozen kinds, with the long heads of Meadow Foxtail particularly prominent - their brown, foxy colouring is due to the covering of pollen-producing anthers. This kind of grassland, still frequent by the Kennet, is nationally in steep decline: most such meadows have been drained and re-sown with agricultural grasses.
Above: Lady's Smock
Other riverside habitats include ungrazed tall fen, made up of Pond Sedge, Meadow Sweet, tall grasses and the occasional patch of reeds, and thickets of willow, sallow and alder. They have spread on land which is no longer grazed or mown for hay, and are rich in wildlife. In addition, there are plantations of poplars, mainly the Grey Poplar, with tall Lombardy Poplars added for amenity, for example, on the river floodplain between Ramsbury Manor and the village. The Kennet has three kinds of willow, the White, the Crack and the scarcer Purple (there is a good example of the latter on the Seven Bridges walk in Ramsbury). Unfortunately, our Crack Willows have become infected with willow scab and canker, probably as a result of the recent mild winters. Many are now moribund, and their loss will change the scenery of the Kennet valley.
Sightings of invasive non-native species should be reported using the plant tracker ap.