nodding groundsel vs wildflower

nodding groundsel and wildflower both are nouns.

Word	Noun	Adjective	Verb	Adverb
nodding groundsel	Yes	No	No	No
wildflower	Yes	No	No	No

As nouns, wildflower is a hypernym of nodding groundsel; that is, wildflower is a word with a broader meaning than nodding groundsel:

nodding groundsel: plant with erect leafy stems bearing clusters of rayless yellow flower heads on bent individual stalks; moist regions of southwestern United States
wildflower: wild or uncultivated flowering plant

Other hypernyms of nodding groundsel include wild flower.

nodding groundsel (noun)	wildflower (noun)
plant with erect leafy stems bearing clusters of rayless yellow flower heads on bent individual stalks; moist regions of southwestern United States	wild or uncultivated flowering plant