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

H. aciferum grows in a mat on the ground and has twisting branches, needle-like leaves, and long golden petals.

This trait is unique within the genus Hypericum to H. aciferum, H. russeggeri, and H. aegypticum, the three species in section Adenotrias.

The species was described by Werner Greuter in 1965 as Elodes acifera, and was later placed into section Adenotrias of the genus Hypericum by Norman Robson in 1984.

Hypericum aciferum has an extremely limited distribution in the southwest corner of Crete, and is found in rock crevices.

The International Union for Conservation of Nature re-assessed H. aciferum as vulnerable in 2021 and recorded its population as stable.

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 species grows low to the ground, with many twisting branches that press against the soil; these form a mat that can be up to 60 cm wide.

The midrib is raised on the underside of the leaf, like the keel of a ship, but is slightly furrowed on the top side.

However, he also said that he did not believe Triadenia was a valid taxon, because specimens of T. microphylla (the type species on which the genus was based) were found to actually be Hypericum aegypticum.

[6] The new name was affirmed in the species catalogue Flora Europaea two years later,[8] and Werner Greuter corroborated the placement in Annales Musei Goulandris in 1973.

[9] While section Adenotrias also possesses those adaptations, it was retained in the genus, meaning that the name Hypericum aciferum remained constant;[10] this was affirmed by a study of molecular phylogenetics in 2013.

[4] Hypericum aciferum can be found among several other species, including Allium bourgeaui, Centaurea argentea, Dianthus fruticosus, Origanum dictamnus, Ornithogalum creticum, and Staehelina fruticosa.

[17] In 1994 the European Environment Agency marked Hypericum aciferum as a "strictly protected flora species".