mountain rice vs silk grass

mountain rice and silk grass both are nouns.

Word	Noun	Adjective	Verb	Adverb
mountain rice	Yes	No	No	No
silk grass	Yes	No	No	No

As nouns, mountain rice and silk grass are synonyms defined as:

mountain rice and silk grass: valuable forage grass of dry upland areas and plains of western North America to northern Mexico

Other synonyms of mountain rice include Indian millet, Oryzopsis hymenoides, silkgrass.

mountain rice (noun)	silk grass (noun)
valuable forage grass of dry upland areas and plains of western North America to northern Mexico	valuable forage grass of dry upland areas and plains of western North America to northern Mexico