Micromeria glomerata

Micromeria glomerata, known locally as cliff thyme (Spanish: tomillo de risco) or thyme of Taganana, is a species of plant with woody chameleophyte flowers, belonging to the Lamiaceae family.«Detalles de la especie : Micromeria glomerata P.Pérez». Catalogue of Life. Accessed on July 11, 2019. It is a species endemic to the northeast of the Canary Island of Tenerife, whose description was first made in 1974, thanks to botanist Pedro Luis Pérez de Paz.«Micromeria glomerata P.Pérez, Vieraea 3: 78 (1973 publ. 1974)». Kew Science. Accessed on July 11, 2019. It is a medicinal and aromatic plant with pink-purple flowers that grows at low altitude in the crevices of the slopes«Familia Lamiaceae». Flora de las Islas Canarias. Accessed on July 11, 2019.«Micromeria varia». Flora de Canarias. Accessed on July 11, 2019. of the protected area of the Anaga Rural Park, located in the massif of the same name.«Micromeria glomerata P.Perez». Global Biodiversity Information Facility. Accessed on July 11, 2019.«Micromeria glomerata». Atlas y Libro Rojo de la Flora Vascular Amenazada de España. Accessed on July 11, 2019. The flexible, puberulose stemIn botany, the term pubescent refers to any plant organ (leaf, fruit) or plant set that has a hairy surface, covered with fine, short hairs. and with internodes can reach 10 to 40 centimeters in height.Pérez de Paz, 1974, p. 79. On the other hand, the leaves are small and flat, 8 mm long by 6 mm wide.11

In 1991, R. H. Willemse confused it with what he believed to be a new species, so he gave it the name of Satureja anagae, although this was eventually rejected.«Satureja anagae». The Plant List. Accessed on October 5, 2018. Its holotype, dated May 27, 1972, is kept in the herbarium of the University of La Laguna.«Holotype of Micromeria glomerata P. Pérez [family LABIATAE]». Pedro Pérez de Paz. Accessed on October 2, 2018. Due to its small distribution and threats in its habitat, it is considered critically endangered. Some botanical gardens are involved in its conservation, such as the Conservatoire botanique national de Brest, which listed it in 2008.«Rapport 2008». Conservatoire botanique national de Brest. 2008. Accessed on August 1, 2015.

Description

Vegetative apparatus

Micromeria glomerata is a chameleophytic plant,Santos Guerra y Romero Manrique, 1996, p. 432. whose holotype, collected on May 27, 1972,«Occurrences of Micromeria glomerata». Global Biodiversity Information Facility. Accessed on July 11, 2019. is kept in the herbarium of the University of La Laguna. Depending on its habitat, Micromeria glomerata produces small woody stems, simple or branched, vertical or ascending, between 10 and 40 centimeters above the ground. These stems are flexible and puberulous, with very short internodes. In addition, the cortex of older ones turns red. At the top of the stems, the branching is dense and rather thin.

The leaves are small and flat (8 millimeters long and 6 millimeters wide), oval or lanceolate (lance-shaped), sessile or slightly petiolate, nervomarginalized,The Latin term nervosomarginiltis is used only by Pérez de Paz to describe the species of the genus Micromeria. closely interlaced and often tinged redGonzález González, 2011, p. 402. by anthocyanins, especially when highly exposed to the sun. These pigments play a photoprotective role: by absorbing UV rays, they reduce photoinhibitionLee, D.W. and Lowry, J.B., «Young-leaf anthocyanin and solar ultraviolet», Biotropica 12, 1980, p. 75–76. and photooxidation, acting as a shield for DNA and cellular components.Burger J & Edwards GE (1996). Plant Cell Physiol, ed. Photosynthetic efficiency, and photodamage by UV and visible radiation, in red versus green leaf Coleus varieties. p. 395-399. The lower part of the leaves is slightly tomentose, and the upper part is glabrous and bright green.

Reproductive system

The flowers are about one centimeter long and are pink-purple in color; they grow clustered at the end of the annual branches, attached to the apex. Three to ten pedicellate flowersThe adjective pedicellate is used to describe flowers that are provided with pedicels, meaning the structure that joins the flower to the branch that supports it. grow on pedunculate stems, which have linear lanceolate hairy bracts 2 to 6 millimeters long.

The spicaster -inflorescences in the ears of the verticillium- forms a ring that completely hides the leaves. The cylindrical tubular calyx is slightly flared, with 13 to 15 ribs about 8 millimeters wide, bilabiate and subcutaneous teeth, hairy on the outside, glabrous on the inside and tinged with red. The corolla is about twice as long as the calyx, purple, hairy on the upper outer part of the tube and outside the leaf blade. The nuculae are oblong.

Evolution

A phylogenetic study of Micromeria has shown that this genus, although monophyletic, has been divided into two subgenera, one exclusive to peninsular Spain and Morocco, and the other to the Canary Islands, including Tenerife.Puppo, 2014, p. 1876. Furthermore, the Canary subgenus can be divided into three, based on the analysis of gene clusters. Micromeria glomerata belongs to the group of the three species present in the Macizo de Anaga, while the other two are Micromeria teneriffae and Micromeria rivas-martinezii.Puppo, 2014, p. 1872 The group of Micromeria glomerata is the oldest that has been found in Macizo de Anaga.Puppo, 2014, p. 1971. The time that separates Micromeria glomerata from the last common ancestor of its group is about 8.4 million years, while its most recent version is about 2.7 million years old.Puppo, 2014, p. 1879

The species was officially discovered on February 8, 1972, by Pedro Luis Pérez de Paz during a hike.Pérez de Paz, 1974, p. 77. On March 18 of the same year, Pedro took samples of the plantPérez de Paz, 1974, p. 78. and distinguished Micromeria rivas-martinezii by its morphological characters and ecological niche. The species was officially added to the catalog of Micromeria species specific to the Canary Islands two years later.

The name Micromeria glomerata was proposed by its discoverer in 1974. Locally, it is called thyme,Atlas y libro rojo de la flora amenazada de España, 2004, quoted from Bramwell, 2006, p. 37 cliff thyme or thyme of Taganana. In 1991, R. H. Willemse gives a description of what he believes to be a new species, and gives it the name Satureja anagae. However, it turned out to be the same species discovered by Perez de Paz. The synonym name Satureja anagae is rejected in favor of Micromeria glomerata. On the other hand, the phylogenetic classification of the species has been under discussion since at least August 2015, due to recent findings on the diversification of the genus Micromeria.Puppo, Pamela; Curto, Manuel; Gusmão-Guedes, Joana; Cochofel, Jaqueline; Pérez de Paz, Pedro Luis; Bräuchler, Christian; Meimberg, Harald (agosto de 2015). «Molecular phylogenetics of Micromeria (Lamiaceae) in the Canary Islands, diversification and inter-island colonization patterns inferred from nuclear genes». Molecular Phylogenetics and Evolution (en inglés). vol. 89: p. 160-170.

Distribution and habitat

Micromeria glomerata is endemic to the island of Tenerife, in the Canary Islands, Spain. It grows at an altitude of between 300 and 485 meters, in the protected area of the Anaga Rural Park, located in Macizo de Anaga, near Taganana.«Micromeria glomerata». IUCN Red list. Accessed on October 1, 2018. In 2004, about 490 specimens were counted, divided into two subpopulations with a tendency to increase. One of the endemic subpopulations has 460 individuals, the next has less than 30.Bramwell, 2006, p. 38.

Lithophyte plants grow on steep phonolithic rocks and in crevices of steep slopes that are exposed to the north and northwest.Santos Guerra y Romero Manrique, 1996, p. 432 There are two subpopulations, the larger one covering an area of approximately 2 km2. In total, the territory covers 6500 m2.

Biology Flowering occurs in spring (May and June)Pérez de Paz, 1974, p. 80. and fruiting in summer (July and August).Pérez de Paz, 1974, p. 74. During dispersal, the seeds emerge from the dry calyx and fly away. Micromeria glomerata partially loses its leaves in summer, while the remaining leaves take on a characteristic persistent reddish color.

Endangerment and protection

Within the genus Micromeria, Micromeria glomerata is one of two species classified as critically endangered by the IUCN, the other being Micromeria rivas-martinezii.Puppo, Curto y Maimberg, 2015, p. 743-749. Erosion of its original paleo-island has diminished the ecological niche available over time.Puppo, 2014, p. 1880. In 1996, specimens were threatened by human activities, such as hunting or grazing, which limit their expansion. Propagation of the species in botanical gardens has been proposed to ensure its conservation.Santos Guerra y Romero Manrique, 1996, p. 433. In 2010, efforts were focused on storing the plant in a germplasm bank and eliminating traces of grazing in the Anaga region.González González, 2011, p. 403.

The 2013 IUCN report notes that the sites where it is found are often inaccessible. Predation by rabbits and goats may limit expansion. Hybridization phenomena with Micromeria varia have been reported as a threat to this species. This occurrence is probably related to the short genetic distance between the two species.

Since 2008, the species has been cultivated in tropical greenhouses corresponding to the subtropical oceanic islands of the climate of the Conservatoire botanique national de Brest, following the mission of Mr. Yves Brien in the Canary Islands.

Uses This plant is of commercial interest as a rock border ornament, and is also used as an aromatic plant for its culinary qualities. Its use as a medicinal plant may have contributed to its rarification, although this is more uncertain than for Micromeria rivas-martinezii.

Micromeria glomerata

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