Frog Rush - Juncus ranarius

Alternative names
Juncus ambiguus

Frog Rush is a small rush which usually forms prostrate rosettes. Single stems grow up to about 5 cm or so. Quite characteristic are the shape of the perianth leaves of the flowers: the outer 3 are distinctly longer than the inner 3. Both have membranous margins.

Similar Species

It is most likely to be confused with Juncus bufonius but plants for closer examination can be picked out in the field by the distinctive light brown colour and small clusters of fruits (rather than all flowers spaced out). The best character is the combination of the big blunt fruit and the short blunt inner tepals.

Identification difficulty

Lake margins, saline marshes, often on bare ground.

When to see it

Flowering June to October.

Life History


UK Status

Formerly mainly coastal in Britain but now seems to be spreading inland.

VC55 Status

Rare, but possibly increasing in Leicestershire and Rutland. It was not recorded in the 1979 Flora survey of Leicestershire.

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Leicestershire & Rutland Map


Yellow squares = NBN records (all known data)
Coloured circles = NatureSpot records: 2020+ | 2015-2019 | pre-2015

UK Map