Nesohedyotis
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''Nesohedyotis'' is a
genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of
flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...
s
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 the island of
Saint Helena Saint Helena (, ) is one of the three constituent parts of Saint Helena, Ascension and Tristan da Cunha, a remote British overseas territory. Saint Helena is a volcanic and tropical island, located in the South Atlantic Ocean, some 1,874 km ...
in the South Atlantic Ocean. It 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 ...
Rubiaceae Rubiaceae () is a family (biology), family of flowering plants, commonly known as the coffee, madder, or bedstraw family. It consists of terrestrial trees, shrubs, lianas, or herbs that are recognizable by simple, opposite leaves with Petiole ( ...
(the family that includes
coffee Coffee is a beverage brewed from roasted, ground coffee beans. Darkly colored, bitter, and slightly acidic, coffee has a stimulating effect on humans, primarily due to its caffeine content, but decaffeinated coffee is also commercially a ...
). It is a
monotypic genus In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispe ...
containing the single species ''Nesohedyotis arborea'' ( Roxb.) Bremek., which grows on the central ridge of the island. It is known commonly as the St. Helena dogwood.Cairns-Wicks, R. 2003
''Nesohedyotis arborea''.
The IUCN Red List of Threatened Species 2003. Downloaded on 24 November 2015.
The vernacular name recalls the similarity between its inflorescences and those of ''
Cornus ''Cornus'' is a genus of about 30–60 species of woody plants in the family Cornaceae, commonly known as dogwoods or cornels, which can generally be distinguished by their blossoms, berries, and distinctive bark. Most are deciduous ...
'' species, the
dogwood ''Cornus'' is a genus of about 30–60 species of woody plants in the family Cornaceae, commonly known as dogwoods or cornels, which can generally be distinguished by their blossoms, berries, and distinctive bark. Most are deciduous ...
s of Europe and North America.Percy, D. M., & Cronk, Q. C. B. (1997)
Conservation in relation to mating system in ''Nesohedyotis arborea'' (Rubiaceae), a rare endemic tree from St Helena.
''Biological Conservation'', 80(2), 135-145.
Although it is one of the commoner endemic species on Saint Helena its small population size and small geographical distribution make it endangered. This species is a small, erect tree growing up to 7 meters tall. The leaves are oppositely arranged. They are lance-shaped with a pointed, downcurved "drip tip". The white flowers are 3 or 4 millimeters wide and the fruit is a brown or black capsule. This tree is a
keystone species A keystone species is a species that has a disproportionately large effect on its natural environment relative to its abundance. The concept was introduced in 1969 by the zoologist Robert T. Paine. Keystone species play a critical role in main ...
in the thickets of the island. The leaves collect mist, which condenses and falls from the "drip tips" into the vegetation below, providing water.


See also

*
Flora of St Helena The flora of Saint Helena, an isolated island in the South Atlantic Ocean, is exceptional in its high level of endemism and the severe threats facing the survival of the flora. In phytogeography, it is in the phytochorion St. Helena and Ascension R ...


References


Further reading

* Cronk, Q.C.B. (1995). ''The Endemic Flora of St Helena''. Anthony Nelson Ltd., Oswestry. Monotypic Rubiaceae genera Flora of Saint Helena Endangered plants Spermacoceae {{Rubioideae-stub