Where does “Neptune grass” come from?

Neptune grass (English) comes from English grass, from Middle English gras, from Old English græs, from Proto-West Germanic gras, from Proto-Germanic grasą, from Proto-Indo-European ǵʰreh₁- — to become green, grow; to grow; to green, to grow.

Neptune grass (English): Posidonia oceanica, a seagrass native to the Mediterranean

Definitions

  1. Posidonia oceanica, a seagrass native to the Mediterranean

Ancestry of “Neptune grass”, step by step

Neptune grass traces back through two separate lines of ancestry.

via English grass

StepLanguageWordMeaning
1EnglishgrassAny plant of the family Poaceae, characterized by...
2Middle EnglishgrasA grass; Any plant; especially a herbaceous one;...
3Old Englishgræsgrass
4Proto-West Germanicgrasgrass
5Proto-Germanicgrasągrass
6Proto-Indo-Europeanǵʰreh₁-to become green, grow; to grow; to green, to grow

via English Neptune

StepLanguageWordMeaning
1EnglishNeptuneeighth planet in the solar system
2Middle EnglishNeptune
3LatinNeptūnusNeptune god of the sea
4Proto-Italicneptūnos
5Proto-Indo-Europeannébʰoscloud; mist, moisture
6Proto-Indo-European-osCreates action nouns or result nouns from verbs;...
Every word from Proto-Indo-European ǵʰreh₁-Every word from Proto-Germanic grasąEvery word from Proto-West Germanic gras