Scientific name: Hypericum tetrapterum Fr.
Common name: Square-stalked St. John's-wort
Description
Habit: A hairless perennial, to 60 cm high.
Stems: Erect, stiff, square in section and with distinct but narrow wings wide, with rhizomes.
Leaves: Opposite, entire, stalkless, without stipules, oval, with numerous small translucent glands and few black glands.
Flowers: Yellow, actinomorphic, hermaphrodite, 12-15 mm across, in terminal and axillary cymes; sepals 5, free; petals 5, free, slightly longer than stamens, with few black glands on upper surface; stamens in 3 (rarely 5) bundles; styles 3, ovary superior.
Fruits: A capsule, succulent and berry-like, seeds numerous.
Habitat: Ditches, marshes and damp grassland.
Distribution: Widespread and locally frequent.
Native status: Native
Of conservation interest: No