These are the flowers of Typha latifolia, the common bulrush, growing vigorously along Lambrok Stream.
Bulrushes grow in or near standing water and are increasingly being used to protect streams and ponds from contamination. They reduce the levels of phosphates, nitrogen and harmful bacteria in the water, and increase oxygen levels; they collect silt and solid detritus around their roots, providing habitat for the sort of bacteria that help break down other contaminants.
The female flowers, densely packed brown florets, are at the bottom and the male flowers, usually a lighter brown, are above. The male flowers in these pictures, having produced their pollen much earlier, have shrivelled away. The female flowers will retain their shape and colour until they burst into masses of fluffy seed during the winter.
There are sites in America where artificial reed-beds, planted with bulrushes (or cattail in American parlance) are being used to filter even the toxic acidic runoff from old mines.
If there is to be housing development at Church Lane (H2.4), Upper Studley (H2.5), and Southwick Court (H2.6), Lambrok Stream will need protecting from the runoff, over steep ground, from access roads, gardens, and numerous roofs. Reed beds seem the best possible option: a native species, already well established in the landscape, using well-understood techniques.
There are water vole territories and otter hunting ranges to protect, and the breeding habitats of the reserve’s fourteen species of Odonata. There are bullheads in the stream and caddis fly larvae and the internationally protected opposite leaved pondweed. None of the planning applications submitted to put residential developments in these three allocated sites has included adequate protection for Lambrok Stream and its biodiversity.
Wiltshire Council should insist that developers include reed-beds in their strategies for protecting the stream.
Pictures of bulrushes by DKG