Hypericum sechmenii | |
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Hypericum sechmenii among limestone rocks in its type locality of Günyüzu | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Clade: | Rosids |
Order: | Malpighiales |
Family: | Hypericaceae |
Genus: | Hypericum |
Section: | Hypericum sect. Adenosepalum |
Species: | H. sechmenii
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Binomial name | |
Hypericum sechmenii Ocak & O.Koyuncu
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Approximate distribution of Hypericum sechmenii[1]: 4 |
Hypericum sechmenii, commonly called seçmen kantaronu in Turkish[2] which means Seçmen's St. John's wort in English, is a rare species of flowering plant of the St. John's Wort family (Hypericaceae) that is found only in the Eskişehir Province of central Turkey. It was described by Turkish botanists Atila Ocak and Onur Koyuncu who named the species in honor of Özcan Seçmen, a fellow Turkish botanist. Found in the crevices of exposed limestone, it is a perennial herb which grows in clusters of stems 3–6 centimetres (1.2–2.4 inches) tall and blooms June to July with bright yellow five-petalled flowers. Formally described in 2009, the species was first collected in 2006 and has since been found in only two localities with an estimated population of less than 250.
Description
Hypericum sechmenii is a flowering perennial herb that grows in dense clusters of upright stems typically 3–6 cm (1.2–2.4 in) tall,[3]: 592 sometimes to 8 cm (3.1 in).[4] It has yellow flowers with five petals[1]: 3 that usually bloom in June and July.[3]: 592
Roots
The outside of its roots has a very thick waterproof protective covering made of fats and wax called a cuticle. Directly beneath the cuticle are one to two bark-like layers (called the periderm) which are composed of several layers of dead cells. Beneath the periderm are several layers of thin-walled tissue cells called a cortex. The tissue of the roots is completely covered in elements of water transport tissue called xylem.[1]: 7–8
Stems
The numerous smooth and hairless stems of Hypericum sechmenii have multiple layers. On the outside is a thin cuticle which then covers one layer of epidermis. Beneath this epidermis, there are several layers of oval-shaped peridermal cells consisting of a waxy substance called suberin which helps to waterproof the stems. Some cells in the periderm of the stems also contain inorganic minerals known as druse crystals[1]: 7 which are thought to deter herbivory because of their toxicity.[5]: 6 Beneath the periderm is the main growth tissue called vascular cambium which produces xylem and another transport tissue called phloem in inward and outward directions, respectively.[1]: 7
Leaves
The leaves of Hypericum sechmenii attach directly to the stems, meaning they are sessile (with no leafstalks). They are roughly 2–5 millimetres (mm) long,[4][3]: 592 and they densely overlap each other. The texture of the leaves is described as somewhat leathery (coriaceous). Leaves are either egg-like (ovate) with a broader base, or elliptic in shape with rounded tips and pointed bases (cuneate). There are numerous pale glands on the surfaces of the leaves, and a few black glands can be found on the margins (edges).[3]: 592 These glands can be seen by the naked eye, though in order to see the pale glands the leaf may need to be held up to a light. The pale glands contain and excrete essential oil compounds, while the dark glands contain red-staining naphthodianthrones which deter some herbivorous insects.[6]: 5
On both sides of the leaves there are pores which regulate gas exchange, called stomata, and there is tightly packed photosynthetic tissue just below the epidermis. Some of the cells in this tissue also contain druse crystals. The central vein of the leaf is noticeably larger and more prominent than the lateral veins, giving the leaves a distinct midrib.[1]: 4–5
Inflorescence
The inflorescences (flower clusters) grow on the ends of the stems and will typically have three to five flowers in an arrangement in which there are longer flower stems (pedicels) on the outer flowers than on the inner ones. This gives the cluster a level top creating a structure known as a corymb. The specialized bract leaves which surround the flowers are long and have glands and small hairs called cilia. The leafy structures which provide support for the petals, called the sepals, are roughly 2 mm long, oblong, and can be either pointed or rounded. Their edges also have glands and small hairs, similar to the bracts. However, they may have a few black or amber dots and amber colored lines which the bracts do not.[4][3]: 592 The petals are bright yellow, like most species of Hypericum, and grow in a pentagon of five on each flower.[1]: 3(figure 2) They are 4–7 mm long and have amber glands that can take the shape of dots or short lines. On the edges of the petals are a few black glands as well.[4][3]: 592
The pollen grains of Hypericum sechmenii have three grooves in a triangular layout, and the overall shape of the grain is a slightly elongated sphere. A pollen grain is 17.2 micrometres (μm) long and 11.5 μm wide. Each surface groove is 12.2 μm long and 2.4 μm wide, and the region where the grooves meet is 1.7 μm in diameter. The pores on the surface of the pollen grain are 2.5 μm long and 2.2 μm wide. Their tough outer wall (exine) is 1.5 μm thick and has a sculptured outer layer with a net-like pattern.[3]: 592
The seed capsules are 3–4 mm long and oval in shape, and their ovaries have a few oil cavities (vittae) which run lengthwise along the capsule. The seeds themselves have tiny, regular pits in the shape of small lines or ladders.[3]: 592
Similar species
Hypericum sechmenii is morphologically similar to numerous other Turkish species of Hypericum. In its original description, its similarity to Hypericum huber-morathii and Hypericum minutum was noted, but it has also been closely compared to Hypericum thymopsis.[3]: 592-593 [7]: 151
When compared to Hypericum minutum and H. huber-morathii, Hypericum sechmenii can be differentiated by a number of distinct features. Its leaves are adjacent and overlapping, while the leaves of H. minutum and H. huber-morathii are opposite. Hypericum sechmenii has more flowers on an inflorescence (3–5) than H. minutum (1–3), and usually fewer than H. huber-morathii (3–12). The glands on its petals are also different, as it has amber dots and lines, whereas H. minutum has only amber dots and H. huber-morathii only sometimes has black dots.[3]: 592
Anatomically, Hypericum sechmenii is also similar to H. thymopsis, despite not being as closely related as H. minutum or H. huber-morathii. Both species have similar adaptations in their stomata which make them more able to thrive in dry climates, and both species have stomata on the upper and lower sides of their leaves. However, H. sechmenii has a thinner layer of palisade tissue than H. thymopsis, as well as having its inner layers of stem tissue made up solely of xylem, whereas H. thymopsis also has softer, spongy pith tissue.[7]: 151
Taxonomy
The holotype of the species was first collected in 2006 at Günyüzü by Atila Ocak and is now housed at Eskişehir Osmangazi University.[4] Three years later, in December 2009, the species was formally described in volume 46 of the peer-reviewed journal Annales Botanici Fennici. Hypericum sechmenii was described by Atila Ocak and Onur Koyuncu alongside Filiz Savaroglu and Ismuhan Potoglu, the four of whom are all Turkish botanists.[8] Ocak and Koyuncu gave the species the specific epithet sechmenii as an homage to the prominent Turkish taxonomist and ecologist Özcan Seçmen, and in Turkey the plant is known as seçmen kantaronu, translated as Seçmen's St. John's wort.[2][3]: 592 The species was incorporated into the Flora of Turkey endemic species registry in 2011 alongside another recently decribed Hypericum species, Hypericum musadoganii.[9]: 20
In 1977, British taxonomist Norman Robson began a genus-wide monograph of Hypericum which divided the genus into 36 sections, with almost every species in the genus being placed into one of these sections based on their morphology and phylogeny. However, Hypericum sechmenii was omitted from this original monograph, as it had not yet been identified as a unique species.[10]: 1,4 After Hypericum sechmenii was described, it was then placed into the overall framework of the genus Hypericum by Robson in a later addition to his monograph. Robson corroborated the findings of Ocak and Koyuncu that H. sechmenii was its own species, taking note of its similarities to other Anatolian species of Hypericum, specifically Hypericum minutum and Hypericum huber-morathii. Because of this, Robson placed the species in a clade called the Huber-morathii Group which comprises five Turkish species of Hypericum and lies within the large section Adenosepalum.[4]
Distribution and habitat
Hypericum sechmenii is one of numerous species of Hypericum which are endemic to Turkey. Specifically, the species is endemic to central Turkey in northwestern Anatolia, in Eskişehir Province.[2][11] The species is known only from two separate localities, one near the peak of Arayit Mountain, and the other between the towns of Kaymaz and Sivrihisar.[3]: 591-592 [4] The area of distribution on Arayit Mountain is estimated to be 2 square kilometres (km2) (equivalent of about 1.2 square miles (mi2)). The area of the Kaymaz to Sivrihisar location is estimated to be less.[1]: 8
The species' habitat is usually in and among the crevices of limestone rocks and outcroppings. The leaves of Hypericum sechmenii contain xeromorphic stomata, which are stomata that have developed adaptations to allow the plant to better survive in its arid, steppe habitat of Central Anatolia,[1]: 5 [12] defined as the Irano-Turanian floristic region.[13]: 66 The holotype of the species was collected at about 1,800 metres (5,900 feet), and the general elevation of the species is 1,750–1,820 m (5,740–5,970 ft).[4][3]: 591-592 Several other specimens of H. sechmenii have been collected since the species' discovery, being preserved at different Turkish herbariums.[8]
Type | District | Locality | Habitat | Coordinates | Collection Date | Herbarium | Reference |
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Holotype | Günyüzü | Arayit Mountain | Rock crevices | 39°18'14.6"N, 31°44'51.1"E | 10 June 2006 | Eskişehir Osmangazi University | [3] |
Isotype | Günyüzü | Arayit Mountain | Rock crevices | 39°18'14.6"N, 31°44'51.1"E | 10 June 2006 | Gazi University | [8] |
Isotype | Günyüzü | Arayit Mountain | Rock crevices | 39°18'14.6"N, 31°44'51.1"E | 10 June 2006 | Hacettepe University | [8] |
Sivrihisar | Arayit Mountain | Hilly steppe | 39°17'47.3"N, 31°45'07.3"E | 7 July 2011 | [1] | ||
Sivrihisar | Sivrihisar–Kaymaz | Rocks near Kaymaz | 31°13'56.0"N, 39°32'19.5"E | 13 July 2011 | [1] |
Ecology
Hypericum sechmenii usually flowers June to July, and it fruits in July.[3]: 592
Hypericum sechmenii is found in and among a number of other plant species. Specifically, it grows alongside small shrubs and perennial herbs like stonecress (Aethionema subulatum), woodruff (Asperula nitida), harebell (Asyneuma compactum), small toadflax (Chaenorhinium minus), Kotschy's damask flower (Hesperis kotschyi), flax (Linum cariense), restharrow (Ononis adenotricha), dandelions (Scorzonera tomentosa), Turkish catchfly (Silene falcata), and wood betany (Stachys lavandulifolia). It is found among only one other Hypericum species, which is Hypericum confertum.[3]: 593
Conservation
It is estimated that there are fewer than 250 members of the species that inhabit an area which is approximately 10 km2 (3.8 mi2). The species is under threat from both abiotic factors, especially climate change, as well as human impact from agriculture and grazing. Because of these threats and unhealthy population of Hypericum sechmenii, it was recommended by biologist Koray Yaylaci in 2013 that the species be classified as Critically Endangered by the International Union for Conservation of Nature (IUCN), although no conservational measures have been taken as of February 2021[update].[1]: 8–9
References
- ^ a b c d e f g h i j k l Yaylaci, Ömer; Özgisi, Kurtulus; Sezer, Okan; Orhanoğlu, Gökhan; Öztürk, Derviş; Koyuncu, Onur (2013). "Anatomical studies and conservation status of rare endemic Hypericum sechmenii Ocak&Koyuncu (Sect: Adenosepalum) from Eskişehir - Turkey". Journal of Selçuk University Natural and Applied Science. 2 (1): 1–11. Retrieved 5 February 2021 – via ResearchGate.
- ^ a b c Güner, A.; Aslan, S.; Ekim, T.; Vural, M.; Babaç, M.T. (2013). "Türkiye Bitkileri Listesi (Damarlı Bitkiler)" [Turkish Plants List (Vascular Plants)]. Bizimbit Kiler (www.bizimbitkiler.org.tr) (in Turkish). İstanbul: Nezahat Gökyiğit Botanical Garden and Flora Research Association. Archived from the original on 13 February 2021. Retrieved 13 February 2021.
- ^ a b c d e f g h i j k l m n o p Ocak, Atila; Savaroglu, Filiz; Potoğlu Erkara, İsmuhan; Koyuncu, Onur (2009). "Hypericum sechmenii (Hypericaceae), a new species from Central Anatolia, Turkey" (PDF). Annales Botanici Fennici. 46 (6): 591–594. doi:10.5735/085.046.0616. ISSN 0003-3847. S2CID 86751774. Retrieved 5 February 2021 – via www.sekj.org.
- ^ a b c d e f g h Pattinson, David; Robson, Norman; Nürk, Nicolai; Crockett, Sarah. "Hypericum sechmenii Nomenclature". Hypericum Online (hypericum.myspecies.info). Archived from the original on 13 February 2021. Retrieved 13 February 2021.
- ^ Cuéllar-Cruz, Mayra; Pérez, Karina; Mendoza, María; Morena, Abel (2020). "Biocrystals in plants: a short review on biomineralization processes and the role of phototropins into the uptake of calcium". Crystals. 10 – via MDPI.
- ^ Crockett, Sara; Robson, Norman (January 2011). "Taxonomy and chemotaxonomy of the genus Hypericum". Medicinal and Aromatic Plant Science and Biotechnology. 5. Takamatsu, Japan: Global Science Books: 1–13. ISSN 1752-3389. PMC 3364714. PMID 22662019. Retrieved 13 February 2021 – via National Center for Biotechnology Information (NCBI).
- ^ a b Tekin, Mehmet (April 2017). "Pharmacobotanical study of Hypericum thymopsis". Revista Brasileira de Farmacognosia. 27 (2): 143–152 – via ScienceDirect.
- ^ a b c d International Plant Names Index (IPNI) (2020). "Hypericum sechmenii Ocak & O.Koyuncu, Ann. Bot. Fenn. 46(6): 591 (-594; figs. ) (2009)". IPNI (www.ipni.org). The Royal Botanic Gardens, Kew; Harvard University Herbaria & Libraries; and, Australian National Botanic Gardens. Retrieved 5 February 2021.
- ^ Kaynak, Gönül (2012). Bursa Ve Çevresinde Yaylişi Olan Hypericum L. Taksonlari Üzerinde Taksonomik Ve Korolojik Araştirmalar (PDF) (in Turkish). Uludağ University Institute of Science. p. 20.
- ^ Carine, Mark A.; Christenhusz, Maarten J.M. (14 May 2013). "About this volume: the monograph of Hypericum by Norman Robson". Phytotaxa. 4 (1): 1–4. doi:10.11646/phytotaxa.4.1.1. ISSN 1179-3163.
- ^ POWO (2019). "Hypericum sechmenii Ocak & Koyuncu". Plants of the World Online (powo.science.kew.org). Royal Botanic Gardens, Kew. Retrieved 5 February 2021.
- ^ "Climate of Turkey" (PDF). Meteoroloji Genel Müdürlüğü. Archived from the original (PDF) on 13 February 2015. Retrieved 10 February 2021.
- ^ Talebi, Khosro Sagheb; Sajedi, Toktam; Pourhashemi, Mehdi (22 October 2013). Forests of Iran: A Treasure from the Past, a Hope for the Future. Springer Science & Business Media. ISBN 9789400773714.