short-grass vs shortgrass

short-grass and shortgrass both are nouns.

Word	Noun	Adjective	Verb	Adverb
short-grass	Yes	No	No	No
shortgrass	Yes	No	No	No

As nouns, short-grass and shortgrass are synonyms defined as:

short-grass and shortgrass: any of various grasses that are short and can tolerate drought conditions; common on the dry upland plains just east of the Rocky Mountains

short-grass (noun)	shortgrass (noun)
any of various grasses that are short and can tolerate drought conditions; common on the dry upland plains just east of the Rocky Mountains	any of various grasses that are short and can tolerate drought conditions; common on the dry upland plains just east of the Rocky Mountains