hawk's-beard vs hawk's-beards

hawk's-beard and hawk's-beards both are nouns.

Word	Noun	Adjective	Verb	Adverb
hawk's-beard	Yes	No	No	No
hawk's-beards	Yes	No	No	No

As nouns, hawk's-beard and hawk's-beards are synonyms defined as:

hawk's-beard and hawk's-beards: any of various plants of the genus Crepis having loose heads of yellow flowers on top of a long branched leafy stem; Northern Hemisphere

hawk's-beard (noun)	hawk's-beards (noun)
any of various plants of the genus Crepis having loose heads of yellow flowers on top of a long branched leafy stem; Northern Hemisphere	any of various plants of the genus Crepis having loose heads of yellow flowers on top of a long branched leafy stem; Northern Hemisphere