''Dioscorea chouardii'' (synonym: ''Borderea chouardii'') is a

herbaceous Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials. Definitions of "herb" and "herbaceous" The fourth edition of ...

plant in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Dioscoreaceae Dioscoreaceae () is a family of monocotyledonous flowering plants, with about 715 known species in nine genera. The best-known member of the family is the yam (some species of ''Dioscorea''). The APG system (1998) and APG II system (2003) both ...

. It is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to a single cliff located in the

Pyrenees The Pyrenees are a mountain range straddling the border of France and Spain. They extend nearly from their union with the Cantabrian Mountains to Cap de Creus on the Mediterranean coast, reaching a maximum elevation of at the peak of Aneto. ...

Aragon, Spain Aragon ( , ; Spanish and ; ) is an autonomous communities of Spain, autonomous community in Spain, coextensive with the medieval Kingdom of Aragon. In northeastern Spain, the Aragonese autonomous community comprises three provinces of Spain, ...

History

A previously unknown species, ''Dioscorea chouardii'' was discovered in the 1950s growing in cracks in a limestone cliff in the Pyrenees Mountains in northeastern Spain. The fissures in which it lives are so inaccessible that it proved difficult to estimate the number of plants. At first it was thought that there were some 300 to 500 plants scattered across the rock face, but later, with the erection of some

scaffolding Scaffolding, also called scaffold or staging, is a temporary structure used to support a work crew and materials to aid in the construction, maintenance and repair of buildings, bridges and all other human-made structures. Scaffolds are widely u ...

and the help of

binoculars Binoculars or field glasses are two refracting telescopes mounted side-by-side and aligned to point in the same direction, allowing the viewer to use both eyes (binocular vision) when viewing distant objects. Most binoculars are sized to be held ...

and

telescope A telescope is a device used to observe distant objects by their emission, Absorption (electromagnetic radiation), absorption, or Reflection (physics), reflection of electromagnetic radiation. Originally, it was an optical instrument using len ...

s, individual plants could be monitored, and a total figure of around 9,000 plants was reached.

Taxonomy

''Dioscorea chouardii'' was originally separated from ''

Dioscorea ''Dioscorea'' is a genus of over 600 species of flowering plants in the family Dioscoreaceae, native throughout the tropical and warm temperate regions of the world. The vast majority of the species are tropical, with only a few species extendin ...

'', along with its close relative ''D. pyrenaica'', in the genus ''Borderea'' on the basis of the seeds lacking the wings of most ''Dioscorea'', although it was pointed out by 2001 that other

alpine Alpine may refer to any mountainous region. It may also refer to: Places Europe * Alps, a European mountain range ** Alpine states, which overlap with the European range Australia * Alpine, New South Wales, a Northern Village * Alpine National P ...

species recognised as ''Dioscorea'' in Africa and South America also had wingless seeds.

Ecology

''Dioscorea chouardii'' is related to the yam and grows from a

tuber Tubers are a type of enlarged structure that plants use as storage organs for nutrients, derived from stems or roots. Tubers help plants perennate (survive winter or dry months), provide energy and nutrients, and are a means of asexual reproduc ...

hidden in the rock fissure. From this it sends out a shoot each year which withers away in the autumn. The shoot leaves a scar on the tuber, which makes it possible to estimate the age of the plant from the number of scars; the oldest plants are calculated to have lived for three hundred years, and may be contenders for being the "slowest growing plants in the world". The plant reproduces by seed, pollination having been performed by

ant Ants are Eusociality, eusocial insects of the Family (biology), family Formicidae and, along with the related wasps and bees, belong to the Taxonomy (biology), order Hymenoptera. Ants evolved from Vespoidea, vespoid wasp ancestors in the Cre ...

s. When fertilised, the flower-stem bends over to bury the resulting seedhead in the crack, the seeds being released when it dries. This would limit dispersal possibilities for the plant were it not for the fact that the seeds are transported by ants, which distribute them more widely. Because most ''Dioscorea'' are strictly tropical species, this plant is considered to be what is known as a "

relict species In biogeography and paleontology, a relict is a population or taxon of organisms that was more widespread or more diverse in the past. A relictual population is a population currently inhabiting a restricted area whose range was far wider during a ...

"; a remnant from the warmer temperatures of the

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

. ''Dioscorea chouardii'' is morphologically very similar to another relict species, ''D. pyrenaica'', which has a rather wider distribution in the Pyrenees. The former grows in vertical cracks on shaded, north-facing limestone cliffs at between while the latter grows on limestone screes at over . RAPD testing strongly suggests that ''D chouardii'' is not an

ecotype Ecotypes are organisms which belong to the same species but possess different phenotypical features as a result of environmental factors such as elevation, climate and predation. Ecotypes can be seen in wide geographical distributions and may event ...

of ''D. pyrenaica'' and that the two

taxa In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...

should be considered separate species.

Conservation status

In 1992, under the

synonym A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

''Borderea chouardii'', it was designated as a 'priority species' under Annex II of the

Habitats Directive The Habitats Directive (more formally known as Council Directive 92/43/EEC on the Conservation of natural habitats and of wild fauna and flora) is a directive adopted by the European Community in 1992 as a response to the Berne Convention. The ...

in the

European Community The European Economic Community (EEC) was a regional organisation created by the Treaty of Rome of 1957,Today the largely rewritten treaty continues in force as the ''Treaty on the functioning of the European Union'', as renamed by the Lisbo ...

, which means areas in which it occurs could be declared

Special Areas of Conservation A special area of conservation (SAC) is defined in the European Union's Habitats Directive (92/43/EEC), also known as the ''Directive on the Conservation of Natural Habitats and of Wild Fauna and Flora''. They are to protect the 220 habitats and ap ...

, ''if'' these areas belong to one of the number of

habitat In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...

s listed in Annex I of the directive. Pursuantly in the

European Union The European Union (EU) is a supranational union, supranational political union, political and economic union of Member state of the European Union, member states that are Geography of the European Union, located primarily in Europe. The u ...

, it is now protected by having seven

Natura 2000 Natura 2000 is a network of nature protection areas in the territory of the European Union. It is made up of Special Areas of Conservation and Special Protection Areas designated under the Habitats Directive and the Birds Directive, respectiv ...

sites designated for its protection. The EU has since also officially classified this plant as '

critically endangered An IUCN Red List critically endangered (CR or sometimes CE) species is one that has been categorized by the International Union for Conservation of Nature as facing an extremely high risk of extinction in the wild. As of December 2023, of t ...

'. Although its range is extremely small, the population of this plant seems stable, however, and there is no particular reason why

climate change Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...

should affect it adversely.

References

{{DEFAULTSORT:Dioscorea chouardii chouardii Endemic flora of Spain Endemic flora of the Iberian Peninsula Plants described in 1952