Jointed Rush - Juncus articulatus

Rhizomatous plant, forming dense patches, with erect to prostrate stems, and a stem leaf.  It is very variable.   The leaf is virtually hollow with  very obvious transverse septa which can be felt as ridges across the leaf, but other species share this character.   It is very similar to Sharp-flowered Rush (Juncus acutiflorus), and they do hybridise; according to Stace (4th edn.) the hybrid can be commoner than either species.   

Inflorescences are usually smaller and less branched than J acuitiflorus, and the mature flowers have brown outer tepals that are acute, inner tepals that are acute to rounded. (reference: Stace, 4th edition)

Juncus acutiflorus (Sharp-flowered Rush) and the hybrid between the two

It may not be possible to identify this from a photo, especially of immature or old plants; and be aware of the possibility of hybrids.  Photos showing details of mature inflorescence.   Refer to Stace 4th edition for more information.

Marshes and wet places.

June to September.

Perennial.

Very common throughout Britain.

Quite common in Leicestershire and Rutland. In the 1979 Flora survey of Leicestershire it was found in 296 of the 617 tetrads.