bunch grass vs bunchgrass

bunch grass and bunchgrass both are nouns.

Word	Noun	Adjective	Verb	Adverb
bunch grass	Yes	No	No	No
bunchgrass	Yes	No	No	No

As nouns, bunch grass and bunchgrass are synonyms defined as:

bunch grass and bunchgrass: any of various grasses of many genera that grow in tufts or clumps rather than forming a sod or mat; chiefly of western United States

bunch grass (noun)	bunchgrass (noun)
any of various grasses of many genera that grow in tufts or clumps rather than forming a sod or mat; chiefly of western United States	any of various grasses of many genera that grow in tufts or clumps rather than forming a sod or mat; chiefly of western United States