Salix nigra vs black willow

Salix nigra and black willow both are nouns.

Word	Noun	Adjective	Verb	Adverb
Salix nigra	Yes	No	No	No
black willow	Yes	No	No	No

As nouns, Salix nigra and black willow are synonyms defined as:

Salix nigra and black willow: North American shrubby willow having dark bark and linear leaves growing close to streams and lakes

Other synonyms of Salix nigra include swamp willow.

Salix nigra (noun)	black willow (noun)
North American shrubby willow having dark bark and linear leaves growing close to streams and lakes	North American shrubby willow having dark bark and linear leaves growing close to streams and lakes