grama grass vs gramma grass

grama grass and gramma grass both are nouns.

Word	Noun	Adjective	Verb	Adverb
grama grass	Yes	No	No	No
gramma grass	Yes	No	No	No

As nouns, grama grass and gramma grass are synonyms defined as:

grama grass and gramma grass: pasture grass of plains of South America and western North America

Other synonyms of grama grass include grama, gramma.

grama grass (noun)	gramma grass (noun)
pasture grass of plains of South America and western North America	pasture grass of plains of South America and western North America