old witch grass vs Panicum capillare

old witch grass and Panicum capillare both are nouns.

Word	Noun	Adjective	Verb	Adverb
old witch grass	Yes	No	No	No
Panicum capillare	Yes	No	No	No

As nouns, old witch grass and Panicum capillare are synonyms defined as:

old witch grass and Panicum capillare: North American grass with slender brushy panicles; often a weed on cultivated land

Other synonyms of old witch grass include old witchgrass, tumble grass, witch grass, witchgrass.

old witch grass (noun)	Panicum capillare (noun)
North American grass with slender brushy panicles; often a weed on cultivated land	North American grass with slender brushy panicles; often a weed on cultivated land