Zostera marina vs sea wrack

Zostera marina and sea wrack both are nouns.

Word	Noun	Adjective	Verb	Adverb
Zostera marina	Yes	No	No	No
sea wrack	Yes	No	No	No

As nouns, Zostera marina and sea wrack are synonyms defined as:

Zostera marina and sea wrack: submerged marine plant with very long narrow leaves found in abundance along North Atlantic coasts

Other synonyms of Zostera marina include eelgrass, grass wrack.

Zostera marina (noun)	sea wrack (noun)
submerged marine plant with very long narrow leaves found in abundance along North Atlantic coasts	growth of marine vegetation especially of the large forms such as rockweeds and kelp
	submerged marine plant with very long narrow leaves found in abundance along North Atlantic coasts