This section is from the book "British Wild Flowers - In Their Natural Haunts Vol5-6", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
The margin of a marsh usually shows the wet-meadow type of vegetation that results when marshes are drained. The characteristic tree association may remain to some extent, and Alders and Willows are often found bordering streams and rivers, or growing in hedges with deep or wide ditches, flanked by meadows, which have lost their most characteristic herbaceous marsh flora.
There may be in such wet meadows relics of the former marsh flora, denoted by the general distribution of Marsh Marigold, Lady's Smock (Cardamine amara), Ragged Robin, Great Water Stitchwort, Meadow Sweet, Golden Saxifrage, Marsh Willow Herb, Marsh Bedstraw, Valerian, Marsh Thistle, Moneywort, Scorpion Grass, Water Figwort, Skullcap. Marsh Woundwort, Great Water Dock, Marsh Orchid, Yellow Flag, Hummock Sedge, Tussock Grass (Catabrosa aquatica), Manna Grass, Horsetail, etc.