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Since the original description of the genus, various sections of Hypericum have been accepted as valid and correct taxa. The genus was first divided into sections in 1821, while the modern conception of the genus was established in 1925. Norman Robson formalized the infrageneric classification of Hypericum beginning in 1977, with his monograph of the genus resulting in the creation of 36 sections. Following several phylogenetic studies, Robson revised this organization to include three taxa formerly treated as independent genera, bringing the total number of sections to 39.
History
[edit]The first division of the genus Hypericum in sections was undertaken in 1821 by Jacques Denys Choisy. Choisy established four sections: Ascyreia (based on the previously independent genus Ascyrum), Brathys, Perforaria, and Elodea (at some points treated as the genus Triadenum). Édouard Spach later established many new genera in the family Hypericaceae, and some of these sections were split as such. These were quickly reduced back to infrageneric taxa in 1840 by Stephan Endlicher, but were not specified to be sections.[1]
The modern "wide" conception of Hypericum was first established in 1925 by Robert Keller and Adolf Engler, who recognized 19 sections of the genus. They also created the concept of a section Euhypericum, which encompassed a diverse group of species further divided into more than a dozen subsections. A similar organization was maintained by Arika Kimura in 1951, though several of the sections were restored to generic status.[2]
Under this classification, while some sections of the genus were made up of natural groups of species, others (like Euhypericum) were made up of many unrelated groups. In 1977, Norman Robson began work on a monograph of the genus that sought to organize it according to evolutionary trends.[3] As such, Robson established a provisional slate of 30 sections to be modified as work on the monograph continued.[4] In 2001, Robson had finalized his sectional classification of the genus, ending with 36 total sections.[5]
A 2011 study on the taxonomy and chemotaxonomy of the genus by Robson and Sara Crockett also counted a total of 36 sections in Hypericum.[6] At this point, the sectional relationships of species in the genus were still largely defined by morphological or geographical similarities,[7] and the study used chemotaxonomy to establish biomarkers that confirmed those sectional similarities.[8]
In 2016, Robson published a paper responding to the various phylogenetic studies that had been performed since the conclusion of his monograph, formally describing several clades within the genus. Hypericum was divided into two subgenera called Hypericum and Brathys; the former is made up of species with dark glands which are found primarily in the "Old World", while the latter has species that lack dark glands and are almost all found in the "New World".[9] Several taxa previously treated as genera were also moved into the genus as sections: Lianthus and Thornea retained their names as Hypericum sect. Lianthus and Hypericum sect. Thornea, while Triadenum was renamed as Hypericum sect. Elodea, bringing the genus to a total of 39 sections.[10]
Conventions
[edit]This list follows Norman Robson's classification of the sectional placement of species within Hypericum as outlined in his monograph, unless otherwise noted. The sections are organized alphabetically within their respective subgenera. Species which were added to the genus after the publication of the monograph, and which have had their sectional placement noted by their authors, have been included. Distribution, description, and ecology information are derived from the online version of the monograph, unless otherwise noted.[11]
Sections
[edit]Subgenus Hypericum
[edit]| # | Name | Authority, subdivision, and species | Distribution and habitat | Description | Notes | Vol. |
|---|---|---|---|---|---|---|
| 1. |  |
Considered the basal section of the genus[12] | 5(1) | |||
Subgenus Brathys
[edit]| Name | Authority, subdivision, and species | Distribution | Description and Ecology |
|---|---|---|---|
Two species
|
|||
References
[edit]- ^ Robson 1977, p. 294-295.
- ^ Robson 1977, p. 296-297.
- ^ Robson 1977, p. 306.
- ^ Robson 1977, p. 315.
- ^ Carine & Christenhusz 2010, p. 1-2.
- ^ Crockett & Robson 2011, p. 2.
- ^ Crockett & Robson 2011, p. 3.
- ^ Crockett & Robson 2011, p. 8.
- ^ Robson 2016, p. 191.
- ^ Robson 2016, p. 192.
- ^ Pattinson, David; Robson, Norman; Nürk, Nicolai; Crockett, Sarah. "Hypericum Nomenclature". Hypericum Online (hypericum.myspecies.info). Retrieved 5 February 2021.
{{cite web}}: CS1 maint: url-status (link) - ^ Robson 2016, p. 193.
Bibliography
[edit]- Carine, Mark; Christenhusz, Maarten (2010). "About this volume: the monograph of Hypericum by Norman Robson". Phytotaxa. 4.
- Crockett, Sara; Robson, Norman (2011). "Taxonomy and Chemotaxonomy of the Genus Hypericum" (PDF). Medicinal and Aromatic Plant Science and Biotechnology. 5 (1).
- Robson, Norman (1977). "Studies in the genus Hypericum L. (Guttiferae). 1 Infrageneric Classification" (PDF). Bulletin of the British Museum (Natural History). 5 (6).
- Robson, Norman (2016). "And then came molecular phylogenetics—Reactions to a monographic study of Hypericum (Hypericaceae)". Phytotaxa. 255 (3).