Dahlia

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modern Latin, named in honour of Andreas Dahl (1751–89), Swedish botanist.

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Named 1791 after Anders Dahl, by Spanish botanist Antonio José Cavanilles.

etymonline

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dahlia (n.)

genus of plants native to Mexico and Central America, 1804, named 1791 by Spanish botanist Antonio José Cavanilles for Anders Dahl (1751-1789), Swedish botanist and pupil of Linnaeus, who discovered it for science in Mexico in 1788.

The likelihood that a true blue variety of the flower never could be cultivated was first proposed by French-Swiss botanist Augustin Pyramus de Candolle, and noted in English by 1835; hence blue dahlia, figurative expression for "something impossible or unattainable" (1843).