Question: Lepidium arbuscula is a rare species of flowering plant in the mustard family known by the common names `anaunau and Waianae Range pepperwort, it is endemic to Hawaii, where it is known only from the Waianae Mountains on the island of Oahu, Hawaii (  Hawaiian ) is the 50th and most recent state to have joined the United States of America, having received statehood on which date?

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Lepidium arbuscula: Lepidium arbuscula is a rare species of flowering plant in the mustard family known by the common names `anaunau and Waianae Range pepperwort.  It is endemic to Hawaii, where it is known only from the Waianae Mountains on the island of Oahu.  In 2003 there were ten populations remaining with fewer than 1000 individuals in total.  It is a federally listed endangered species of the US.

Sanicula mariversa: Sanicula mariversa is a rare species of flowering plant in the carrot family known by the common name Waianae Range black-snakeroot.  It is endemic to Hawaii, where it is known only from the Waianae Mountains on the island of Oahu.  It is threatened by the degradation of its habitat.  It is a federally listed endangered species of the United States.

Schiedea kealiae: Schiedea kealiae is a rare species of flowering plant in the pink family known by the common name Waianae Range schiedea.  It is endemic to Hawaii, where it is known only from the Waianae Range on the island of Oahu.  It is threatened by the degradation and destruction of its habitat.  It was federally listed as an endangered species of the United States in 1996.

Tetramolopium lepidotum: Tetramolopium lepidotum is a rare species of flowering plant in the aster family known by the common name Waianae Range tetramolopium.  It is endemic to Hawaii, where today it is known only from the Waianae Mountains on the island of Oahu.  It is threatened by habitat degradation caused by feral goats and pigs and introduced species of plants.

Lobelia oahuensis: Lobelia oahuensis is a rare species of flowering plant in the bellflower family known by the common name Oahu lobelia.  It is endemic to Hawaii, where it is known only from the island of Oahu.  There are about 100 individuals remaining in the Koʻolau Range, and only one known individual in the Waianae Range.  It is federally listed as an endangered species of the United States.

Delissea subcordata: Delissea subcordata is a rare species of flowering plant in the bellflower family known by the common names Koʻolau Range delissea and oha.  It is endemic to Hawaii, where it is known only from the island of Oahu.  It is now only found in the Waianae Mountains, and it is believed to be extirpated from the Koʻolau Range, where it once occurred.  As of 2008 there were 40 individuals remaining, 28 of which were mature plants.  This plant was federally listed as an endangered species of the United States in 1996.

Hawaii: Hawaii ( ; Hawaiian: "" ] ) is the 50th and most recent state to have joined the United States of America, having received statehood on August 21, 1959.  Hawaii is the only U.S. state located in Oceania and the only one composed entirely of islands.  It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean.  Hawaii is the only U.S. state located outside North America.

Kadua degeneri: Kadua degeneri (formerly "Hedyotis degeneri") is a rare species of flowering plant in the coffee family known by the common names Waianae Range starviolet and Degener's bluet.  It is endemic to Hawaii, where it is known only from the island of Oahu.  There are four known populations totalling 370 individuals.  It is a federally listed endangered species of the United States.

Euphorbia kuwaleana: Euphorbia kuwaleana (syn.  "Chamaesyce kuwaleana") is a rare species of flowering plant in the euphorb family known by the common name kokomalei.  It is endemic to Oahu, Hawaii, where it is known only from a four-kilometer stretch of the Waianae Range.  Like other Hawaiian euphorbs, this plant is known locally as `akoko.  It is a federally listed endangered species of the United States.

Cyrtandra dentata: Cyrtandra dentata is a rare species of flowering plant in the African violet family known by the common names mountain cyrtandra and sharp-toothed cyrtandra.  It is endemic to Oahu in Hawaii, where the most recent count estimates 1640 plants occurring in the Waianae Mountains and Koʻolau Mountains.  It is a shrub which can reach 5 meters tall and bears white flowers.  It was federally listed as an endangered species in 1996.  Like other Hawaiian "Cyrtandra" it is called ha`iwale.

Supporting paragraphs: Lepidium arbuscula Hawaii
Answer: August 21, 1959