shortgrass vs short-grass

shortgrass and short-grass both are nouns.

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

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

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

shortgrass (noun)	short-grass (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