Hypericum foliosum, the shining St John's wort, is a species of flowering plant in the family Hypericaceae.

It is a bushy shrub endemic to the Portuguese Azores Islands with golden yellow petals and many stems.

The species was described by William Aiton in 1789 and was later placed into section Androsaemum of the genus Hypericum by Norman Robson in 1984.

It has a diverse essential oil profile made up mostly of monoterpene hydrocarbons, and significant concentrations of various medicinally useful phenols and carotenoids.

The genus name Hypericum is possibly derived from the Greek words hyper (above) and eikon (picture), in reference to the tradition of hanging the plant over religious icons in the home.

The next two rings are an external and internal cortex containing secretory canals, vascular bundles, rows of phloem, and secondary xylem.

[8] The leaves are located on opposite sides of the stem and are shaped like an egg that is stretched to be longer, or similar to a lance.

Each flower is 2.5–3.0 cm wide; when buds, they are shaped between an ellipsoid and an imperfect sphere and are not pointed at the end.

The shape of the sepals varies: they could look like a triangular lance or a flattened ellipse, and their ends can be blunt or pointed.

The ovary is oval-shaped with styles that are 0.5–1.0 cm long and stigmas that end in a distinct narrow head.

[12] It is also highly similar to the hybrid Hypericum × inodorum, but is differentiated by the shape of its sepals and seed capsules.

[11] These compounds are found most densely in the leaves, stem, and bark; the roots, seeds, and flowers have much lower concentrations.

[17] In this original description, based on the type specimen collected on São Miguel in 1777,[6] Aiton noted the species' long petals and sharp calyx as differentiating characteristics.

[6] Norman Robson included the species in an assay of Hypericum as a contribution to the 1968 work Flora Europaea.

[6] It inhabits the laurel and juniper forests of the archipelago,[19] especially in shady and damp areas of mountainous regions at elevations of 220–800 meters.

The rust fungus Melampsora hypericorum takes the form of a pustule on the leaf, damaging the surface.

Larvae of the moth Caloptilia aurantiaca mine into the leaves and later live under the folded tip of the blade.

[20] H. foliosum is not directly endangered by competition with invasive species or human actions;[19] it was listed as Least Concern by the IUCN in 2016.