Pictorial guide to the flora of the British Isles

Home ⟩ Pictorial Guide ⟩ Hypericaceae ⟩ Hypericum tetrapterum / square-stalked St. John’s wort

Hypericum tetrapterum Fr.

square-stalked St. John’s wort (Hypericaceae)

 SpreadBias within British IslesDirection of bias
Very widespreadNegligible tendencyS
Plant Atlas 2020
BSBI Distribution Map

Hypericum tetrapterum grows on riverbanks and in marshes throughout the lowlands, although it is rare in the far north.

Oxford (VC23: Oxfordshire); 2014-07-17

 square-stalked St. John’s wort / Hypericum tetrapterum: _Hypericum tetrapterum_ grows on riverbanks and in marshes throughout the lowlands, although it is rare in the far north.

The flowers of Hypericum tetrapterum are up to 13 mm (½ in) across.

Oxford (VC23: Oxfordshire); 2014-07-17

 square-stalked St. John’s wort / Hypericum tetrapterum: The flowers of _Hypericum tetrapterum_ are up to 13 mm (½ in) across.

The stems of Hypericum tetrapterum have 4 wings along their corners, up to 0.5 mm wide.

Oxford (VC23: Oxfordshire); 2014-07-17

 square-stalked St. John’s wort / Hypericum tetrapterum: The stems of _Hypericum tetrapterum_ have 4 wings along their corners, up to 0.5 mm wide.

The fruit of Hypericum tetrapterum is a 3-valved capsule.

Oxford (VC23: Oxfordshire); 2011-10-14

 square-stalked St. John’s wort / Hypericum tetrapterum: The fruit of _Hypericum tetrapterum_ is a 3-valved capsule.

All images copyright © Christopher J. Dixon unless otherwise indicated.

L-R: Bidens tripartita, Melilotus officinalis, Mimulus guttatus, Thalictrum flavum, Ranunculus peltatus, Anchusa arvensis, Malva alcea, Lolium perenne