great duckweed vs water flaxseed

great duckweed and water flaxseed both are nouns.

Word	Noun	Adjective	Verb	Adverb
great duckweed	Yes	No	No	No
water flaxseed	Yes	No	No	No

As nouns, great duckweed and water flaxseed are synonyms defined as:

great duckweed and water flaxseed: cosmopolitan except South America and New Zealand and some oceanic islands

Other synonyms of great duckweed include Spirodela polyrrhiza.

great duckweed (noun)	water flaxseed (noun)
cosmopolitan except South America and New Zealand and some oceanic islands	cosmopolitan except South America and New Zealand and some oceanic islands