The genus Hypericum contains approximately 500 species which are divided into 36 sections as described by botanist Norman Robson.
[2] This division into distinct sections is largely due to the fact that a genus-wide monograph was performed by Robson in 1977, which allowed for a comprehensive analysis of the genus's taxonomy.
[3] Most of its species contain hypericin or hyperforin and some are used for their healing properties in folk medicine.
Several species are also used for their medicinal properties, especially their ability to alleviate mild clinical depression, by drawing out the oily extract from the flowers.
Adenosepalum is made up of primarily perennial herbs, and also includes shrubs and shrublets.
Species in Adenosepalum are glabrous or have simple hairs, and almost always have dark black glands on their leaves, sepals, and rarely on their petals and stems.
[71] Arthrophyllum contains shrubs that grow to be approximately 0.9 meters tall and are deciduous but never leafless.
Their leaves are placed opposite and are either decussate, sessile, free, or perfoliate and have no ventral glands.
& Spach (1842) Hayek & Siehe (1914) Ascyreia Choisy contains exactly 50 species and also includes four nothospecies.
The section is synonymous with Norysca Spach..[7] Ascyreia is made up of mostly shrubs or shrublets, but also contains a few trees.
Brathys contains a wide variety of plants, including small trees, shrubs, shrublets, and herbs.
The species' stems sprout from branching rhizomes, and are glabrous and lack dark glands.
The stems are white and pubescent with 5–35 millimeter long internodes that can be either shorter or longer than the leaves.
N.Robson (1967) Campylosporus (Spach) R. Keller contains ten species from Africa and the Middle East.
The section contains primarily shrubs and trees that can be spreading or grow up to twelve meters tall.
Its stems are erect or ascend from taproots and have dark glands, and change from 4-lined to 2-lined as the species grows.
The species in the section are low dwarf shrubs or perennial herbs that grow up to 60 centimeters tall.
The leaves are glabrous or paperlike, with stems that branch from the taproot and that have dark red and black glands.
Their stems are narrow and eglandular and have dark black or amber glands on raised lines.
The leaves have dark glands on them and are placed opposite, are decussate, and grow about a centimeter long.
Species in the section have one to seventy flowers regularly, but can have up to 124 in some circumstances, and they grow from one to four different nodes.
The leaves are placed opposite, are decussate and free, and their blades are entire and either closed or open, with pale glands.
Evans Ohwi (1937) A.Rich (1847) R.Keller (1908) Hypericum, sometimes referred to as the "type section" of the genus, contains perennial herbs and very few subshrubs.
The leaves are placed opposite or abnormally whorled, are decussate, and are either sessile or pseudopetiolate, as well as being free and persistent.
The section contains small perennial herbs that grow up to 40 centimeters tall.
(1834) Myriandra (Spach) R. Keller contains shrubs, shrublets, and perennial herbs that grow to be up to 4.5 m. (L.) Crantz (Small) W.P.
The species of the section are found in the mountain ranges of Turkey and the Levant, and several are confined to the island of Socotra.
(2010) Banks & Solander Balf.f (1882) Poulter (1954) Balf.f (1882) Trigynobrathys (Y. Kimura) N.Robson contains shrubs and subshrubs as well as annual and perennial herbs that are very diverse in size and shape.
[139] N.Robson (1985) Webbia (Spach) R. Keller contains a large deciduous shrub that can grow up to 4 meters tall.
The oldest fossil recovered was a seed belonging to the species H. antiquum which was found in Northern Asia.