melilot vs ligneous plant

melilot and ligneous plant both are nouns.

Word	Noun	Adjective	Verb	Adverb
melilot	Yes	No	No	No
ligneous plant	Yes	No	No	No

As nouns, ligneous plant is a hypernym of melilot; that is, ligneous plant is a word with a broader meaning than melilot:

melilot: erect annual or biennial plant grown extensively especially for hay and soil improvement
ligneous plant: a plant having hard lignified tissues or woody parts especially stems

Other hypernyms of melilot include woody plant.

melilot (noun)	ligneous plant (noun)
erect annual or biennial plant grown extensively especially for hay and soil improvement	a plant having hard lignified tissues or woody parts especially stems