black salsify vs viper's grass

black salsify and viper's grass both are nouns.

Word	Noun	Adjective	Verb	Adverb
black salsify	Yes	No	No	No
viper's grass	Yes	No	No	No

As nouns, black salsify and viper's grass are synonyms defined as:

black salsify and viper's grass: perennial south European herb having narrow entire leaves and solitary yellow flower heads and long black edible roots shaped like carrots

Other synonyms of black salsify include scorzonera, Scorzonera hispanica.

black salsify (noun)	viper's grass (noun)
long black salsify	perennial south European herb having narrow entire leaves and solitary yellow flower heads and long black edible roots shaped like carrots
perennial south European herb having narrow entire leaves and solitary yellow flower heads and long black edible roots shaped like carrots