Editing Hypericum (section)

==Description==
[[File:Hypericum hidcoteense.jpg|left|thumb|Hypericum hidcoteense]]
[[File:Rijpe vruchten van Hertshooi (Hypericum). 17-08-2024 (d.j.b.).jpg|thumb|left|Ripe berries of ''Hypericum androsaemum'']]
''Hypericum'' species are quite variable in habit, occurring as trees, shrubs, annuals, and perennials. Trees in the sense of single stemmed woody plants are rare, as most woody species have multiple stems arising from a single base. Shrubs have erect or spreading stems but never root from nodes that touch the ground. However, perennial herbs tend to root from these horizontal nodes, especially those that occur in wet habitats. Annual herbs tend to have [[taproot]]s with a developed system of secondary hair roots. Many species of ''Hypericum'' are completely glabrous, others have simple uniseriate hairs, and some species have long, fine hairs.<ref name=Chemo>{{cite journal |title= Taxonomy and chemotaxonomy of the genus Hypericum |last2= Crocket |first2= Sara L. |last1= Robson |first1= Norman K. B. |journal= Medicinal and Aromatic Plant Science and Biotechnology |volume= 5 |pages= 1–13 |number= Special Issue 1 |year= 2011 |publisher= Europe PMC Funders |pmc= 3364714 |pmid= 22662019 }}</ref>

[[File:Hypericum-perforatum(Blatt).jpg|thumb|Glandular dots on a leaf of ''[[Hypericum perforatum]]'']]
Two types of glands form the characteristic punctiform patterns of ''Hypericum'', "dark glands" and "pale glands". Dark glands consist of clusters of cells with a distinct black to reddish color. Their hue is indicative of a presence of [[naphthodianthrone]], either [[hypericin]] or pseudohypericin, or both. These glands occur in about two-thirds of ''Hypericum'' sections and are usually restricted to certain organs. When these glands are crushed, the naphthodianthrones give a red stain. [[Paracelsus]] called the red secretions "Johannes-blut" in the 16th century, linking the plant to the martyr [[John and Paul|St. John]] and giving rise to the English and German common names of "St. John's wort". The pale glands, forming the pellucid dots, are each a [[wikt:schizogenous|schizogenous]] intracellular space lined with flattened cells that secrete oils and [[phloroglucinol]] derivates, including [[hyperforin]]. The distribution of these hypericin glands dissuades [[Generalist species|generalist]] herbivores from feeding on the plants. When generalist insects feed on ''[[Hypericum perforatum]]'', 30-100% more naphthodianthrones are produced, repelling the insects.<ref name=Chemo/>

[[File:Hypericum subalatum stem.jpg|thumb|The four-lined stem of ''[[Hypericum subalatum]]'']]
The four thin ridges of tissue along the stems are closely to the opposite-decussate leaves of ''Hypericum''. The ridges can be minor, just being called "ridges", or prominent, being called "wings". [[Terete]], two-lined, and six-lined stems can occur occasionally. When a species has a tree or shrub habit, the internodes become mostly terete with age, though some trace of lines can still be detected in mature plants. The number of lines is an important distinguishing characteristic; for example, ''H. perforatum'' and ''Hypericum maculatum'' are easily confused save for ''H. perforatum'' having two lines and ''H. maculatum'' having four. The pale and dark glands are present on stems of various species, and other various species have stems without any glands. In section ''Hypericum'', the glands are only present on stem lines, and in other sections, including ''Origanifolia'' and ''Hirtella'', the glands are distributed across the stems.<ref name=Chemo/>

Nearly all leaves of ''Hypericum'' species are arranged opposite and decussate, an exception being section ''Coridium'' in which whorls of three to four leaves occur. The leaves lack [[stipule]]s and can be sessile or shortly [[Petiole (botany)|petiolar]], though long petioles exist in sections ''Adenosepalum'' and ''Hypericum''. Basal articulation can be present, in which case leaves are deciduous above the articulation, or absent, in which case the leaves are persistent. Some species in sections ''Campylosporus'' and ''Brathys'' have an [[Auricle (botany)|auricle]]-like, reflexed leaf base, whereas true auricles only exist in sections ''Drosocarpium'', ''Thasia'', and ''Crossophyllum''. [[Leaf venation|Laminar venation]] is highly variable, being dichotomous to pinnate to densely reticulate. Leaves are typically ovoid to elongate to linear in shape. Leaves are typically shorter than the internodes. Pale or dark glands can be present on or near the leaf margin and on the main leaf surface.<ref name=Chemo/>

Typically there are four or five [[sepal]]s, though in section ''Myriandra'' there are rarely three. When five sepals are present they are quincuncial, and when four sepals are present they are opposite and decussate. Sepals can be equal or unequal. Sepals can be united at their base, as seen in sections ''Hirtella'', ''Taeniocarpium'', and ''Arthrophyllum''. The margins are variable, having marginal glands, teeth, or hairs. The presence or absence of dark glands on the sepals is a useful distinguishing characteristic.<ref name=Chemo/>

[[File:Hypericum.flower.750pix.jpg|thumb|Yellow petals of ''Hypericum'' x ''hidcoteense'' 'Hidcote']]
Almost all ''Hypericum'' petals are yellow, though a range of color exists from a pale lemony hue to a deep orangish-yellow. Exceptions include the white or pinkish petals of [[Hypericum albiflorum|''Hypericum albiflorum'' var. ''albiflorum'']] and ''[[Hypericum geminiflorum|H. geminiflorum]]''. Many species have petals that are lined or tinged with red, including the deep crimson petals of [[Hypericum capitatum|''H. capitatum'' var. ''capitatum'']]. Petal lengths can be equal or unequal. The petals are mostly asymmetrical except those of sections ''Adenotrias'' and ''Elodes''. In those two sections, sterile bodies have developed between the [[stamen]] [[Fascicle (botany)|fascicle]]s, working as lodicules to spread the petals of the pseudotubular flower, a specialized pollination mechanism. Nearly all species have glands on their petals; only section ''Adenotrias'' has completely eglandular petals. It has been hypothesized that the intensity of red on the petals is correlated with the hypericin content of the glands, but other pigments including [[skyrin]] derivatives can create a red color.<ref name=Chemo/>

''Hypericum'' flowers have four or five fascicles that have, in total, five to two hundred stamens. The fascicles can be free or fused in various ways, often into three apparent fascicles. In sections ''Myriandra'', ''Brathys'', and some of ''Trigynobrathys'', the stamens form a ring. Though stamens are usually persistent, some are deciduous. The stamens have an [[anther]] gland on the connective tissue, varying in color from amber to black.<ref name=Chemo/>

The [[Ovary (botany)|ovaries]] are three or five-merous, occasionally two-merous, with a corresponding number of free or united [[Style (botany)|style]]s. Developing seeds are borne on axile or parietal placentae, with at least two ovules per placenta. ''Hypericum'' fruits are dissimilar to most of [[Hypericaceae]], being capsular and dehisce from the apex. The [[seed capsule|capsule]] can be dry or remain fleshy when mature. The capsules have elongate or punctate glands on their surface that create various shapes and patterns. These glands are typically pale amber, though in section ''Drosocarpium'' the glands are reddish-black. Extractions of these glands in certain species yielded [[phloroglucinol]] and [[terpenoid]] derivatives, suggesting a connection between these glands and the pale glands of vegetative tissue. Seeds of ''Hypericum'' species are small and range in color from a yellowish brown to dark purplish brown. The seeds are cylindric to ellipsoid and may have narrow wings. In some seeds, a basal ridge may be present, and rarely in section ''Adenotrias'' an apical caruncle is present which attracts ants to disperse seeds. Some species have highly specific germination and survival condition requirements. For example, ''[[Hypericum lloydii|H. lloydii]]'' is susceptible to a fungal infection as a seedling if conditions are too moist, whereas other species including ''[[Hypericum chapmanii|H. chapmanii]]'' can grow underwater.<ref name=Chemo/>