Question: Which genus was described first, Dendrobium of Barringtonia?

Context paragraphs:
Pogonoloma: Pogonoloma is a mushroom genus in the family Tricholomataceae in a broad sense.  The genus contains two species known from Europe.  "Pogonoloma" was described first as a subgenus of the genus "Porpoloma" but recent molecular evidence separates the two by several other genera, with "Porpoloma" remaining within a smaller family Tricholomataceae.

Choconta (genus): Choconta is a genus of froghoppers in the family of "Cercopidae".  The genus has been described first by Fennah in 1979.

Sinibrama wui: Sinibrama wui is a species of ray-finned fish in the genus "Sinibrama" which is endemic to China.  It is the type species of the genus "Sinibrama" but there is some controversy as to which form was described first.  If the form descrinbed by S.Y Lin in 1932 is considered specifically distinct from that described by Rendahl then the form named by Rendahl should revert to the binomial "Sinibrama typus".

Choconta circulata: Choconta circulata is a species of froghopper in the genus "Choconta", of the family of Cercopidae.  The species has been named formerly "Sphenorhina circulata" (Lallemand), "Tomaspis circulata" (Fennah), and originally "Cercopis circulatus".  The species has been described first by French entomologist Félix Édouard Guérin-Méneville in 1844.

Species (metaphysics): Species, in metaphysics, is a specific genus-differentia defined item that is described first by its genus (genos) and then its differentia (diaphora).  Put differently, it is an item, not necessarily biological, that belongs to a group and can be distinguished from other species in that group.

Dendrobium: Dendrobium is a huge genus of orchids.  It was established by Olof Swartz in 1799 and today contains about 1,200 species.  The genus occurs in diverse habitats throughout much of south, east and southeast Asia, including China, Japan, India, the Philippines, Indonesia, Australia, New Guinea, Vietnam, and many of the islands of the Pacific.  The name is from the Greek "dendron" ("tree") and "bios" ("life"); it means "one who lives on trees", or, essentially, "epiphyte".

Barringtonia: Barringtonia is a genus of flowering plants in the family Lecythidaceae first described as a genus with this name in 1775.  It is native to Africa, southern Asia, Australia, and various islands of the Pacific and Indian Oceans.  The genus name commemorates Daines Barrington.

Dendrobium begaudii: Dendrobium begaudii is a species of orchid native to New Caledonia.  It was first described by William Cavestro in 2001 under the name Diplocaulobium begaudii but was subsequently referred to the genus Dendrobium by Schuiteman & Adams.

Neotibicen tibicen: Neotibicen tibicen also called the swamp cicada or morning cicada, is a medium-sized, dark-bodied annual cicada widespread across much of the eastern and central United States.  This species is reproductively active particularly in the morning, hence its common name morning cicada.  It used to be widely known as "Tibicen chloromerus", but in 2005 the name was changed to "Tibicen tibicen" because the species was determined to have been described first under this specific epithet.  Likewise, the name of this cicada was changed again in July 2015 due to taxonomic reconfiguration and evaluation of genetics and physiology of the genus "Tibicen".  The genus "Tibicen" is now restricted to only a few European cicada species.  This is the most frequently encountered "Neotibicen" species because males prefer to sing from low branches of trees.  There are two poorly defined subspecies, "N. tibicen tibicen" and "N. tibicen australis".  The latter is restricted to peninsular Florida and southern Georgia, while the former is found throughout the eastern and southern United States.  "N. tibicen" is readily confused with "Neotibicen lyricen", which is similar in body coloration.  "N. tibicen" is of no economic importance.

Supporting paragraphs: Dendrobium Barringtonia
Answer: Barringtonia