gravelweed vs crown beard

gravelweed and crown beard both are nouns.

Word	Noun	Adjective	Verb	Adverb
gravelweed	Yes	No	No	No
crown beard	Yes	No	No	No

As nouns, crown beard is a hypernym of gravelweed; that is, crown beard is a word with a broader meaning than gravelweed:

gravelweed: perennial herb with yellow flowers; southern and south central United States
crown beard: any plant of the genus Verbesina having clustered white or yellow flower heads

Other hypernyms of gravelweed include crown-beard, crownbeard.

gravelweed (noun)	crown beard (noun)
perennial herb with yellow flowers; southern and south central United States	any plant of the genus Verbesina having clustered white or yellow flower heads