The quality or state of being gramineous; the characteristic of resembling or belonging to the grass family.
From 'gramineous' plus the noun-forming suffix '-ness.' This abstract noun formation is typical of English but rarely appears in actual use, remaining mostly a theoretical possibility.
This is a word that technically exists but almost nobody uses—it's what happens when you apply English word-building rules to scientific terms that don't really need abstract nouns!
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