blue toadflax vs old-field toadflax

blue toadflax and old-field toadflax both are nouns.

Word	Noun	Adjective	Verb	Adverb
blue toadflax	Yes	No	No	No
old-field toadflax	Yes	No	No	No

As nouns, blue toadflax and old-field toadflax are synonyms defined as:

blue toadflax and old-field toadflax: North American plant having racemes of blue-violet flowers

Other synonyms of blue toadflax include Linaria canadensis.

blue toadflax (noun)	old-field toadflax (noun)
North American plant having racemes of blue-violet flowers	North American plant having racemes of blue-violet flowers