Hercules'-clubs vs Hercules'-club

Hercules'-clubs and Hercules'-club both are nouns.

Word	Noun	Adjective	Verb	Adverb
Hercules'-clubs	Yes	No	No	No
Hercules'-club	Yes	No	No	No

As nouns, Hercules'-clubs and Hercules'-club are synonyms defined as:

Hercules'-clubs and Hercules'-club: densely spiny ornamental of southeastern United States and West Indies

Other synonyms of Hercules'-clubs include Hercules-club, Zanthoxylum clava-herculis.

Hercules'-clubs (noun)	Hercules'-club (noun)
densely spiny ornamental of southeastern United States and West Indies	densely spiny ornamental of southeastern United States and West Indies
	small deciduous clump-forming tree or shrub of eastern United States