Hypericum tetrapterum

Hypericum tetrapterum (syn. H. quadrangulum) is a herbaceous perennial plant species in the flowering plant family Hypericaceae. Its common names include St. Peter's wort, Peterwort, square stemmed St. John's wort, and square stalked St. John's wort.

Hypericum tetrapterum
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Rosids
Order:	Malpighiales
Family:	Hypericaceae
Genus:	Hypericum
Section:	Hypericum sect. Hypericum
Subsection:	H. subsect. Hypericum
Series:	Hypericum ser. Hypericum
Species:	H. tetrapterum
Binomial name
Hypericum tetrapterum Fries[1]
Synonyms
Hypericum quadrangulum

Description

Hypericum tetrapterum is a rhizomatous, glabrous perennial plant growing up to 1.2 m (3 ft 11 in) in height.[1][2]^:340 The stems are square in cross section, with conspicuous wings at the corners. The leaves are in opposite pairs, simple and entire, and have many translucent glandular dots. The thinly papery leaves are up to 40 mm (2 in) long and 24 mm (0.9 in) across and paler underneath.[1] The flowers are produced in flowerheads of 10–30 flowers (up to 70), each flower 10–15 mm (0.39–0.59 in) in diameter with 5 pale yellow petals and 5 sepals.[1] There may be black glands on the petals and sepals, as well as on the leaves.[2]

Distribution and habitat

Hypericum tetrapterum is common in damp habitats such as marshes, streamsides, open ditches, meadows, and springs throughout Europe.[3][1]

References

1. "Hypericum tetrapterum Fr". hypericum.myspecies.info. Retrieved 2018-10-26.
2. Stace, C. A. (2010). New Flora of the British Isles (Third ed.). Cambridge, U.K.: Cambridge University Press. ISBN 9780521707725.
3. "Hypericum tetrapterum L." Retrieved 19 August 2015.