The stems of this rush are as the name suggests very thin and light green in colour so when you see a sward it looks quite different from the common rushes Juncus effusus (Soft Rush) and Juncus inflexus (Hard Rush) which also like wet ground. In fact both these common rushes were present in the permanent vegetation which grows at the top of the maximum level of the reservoir. Juncus filiformis grows as the water level decreases and it colonises the drying slopes along with other flora such as Persicaria maculosa (Redshank), Persicaria hydropiper (Water Pepper), Limosella aquatica (Mudwort) and unexpectedly Spergula arvensis (Corn Spurrey). This is another plant which although classified as rare nationally was abundant at this site.

The stems of Juncus filiformis are faintly ridged, the fruit nearly spherical and it tends to grow in rows. It was a shy flowerer at this site. J. filiformis grows at several sites in northern England and a few in Scotland but is otherwise very rare. It is absent from Ireland.

Slopes of Stocks reservoir Near Slaidburn, 22nd September 2005

Added on 23rd September 2005, updated February 11th 2010, updated 13th April 2010