black rockweed vs bladder fucus

black rockweed and bladder fucus both are nouns.

Word	Noun	Adjective	Verb	Adverb
black rockweed	Yes	No	No	No
bladder fucus	Yes	No	No	No

As nouns, black rockweed and bladder fucus are synonyms defined as:

black rockweed and bladder fucus: a common rockweed used in preparing kelp and as manure

Other synonyms of black rockweed include bladderwrack, Fucus vesiculosus, tang.

black rockweed (noun)	bladder fucus (noun)
a common rockweed used in preparing kelp and as manure	a common rockweed used in preparing kelp and as manure