pearlweed vs pearl-weed

pearlweed and pearl-weed both are nouns.

Word	Noun	Adjective	Verb	Adverb
pearlweed	Yes	No	No	No
pearl-weed	Yes	No	No	No

As nouns, pearlweed and pearl-weed are synonyms defined as:

pearlweed and pearl-weed: any of various low-growing plants of the genus Sagina having small spherical flowers resembling pearls

Other synonyms of pearlweed include pearlwort.

pearlweed (noun)	pearl-weed (noun)
any of various low-growing plants of the genus Sagina having small spherical flowers resembling pearls	any of various low-growing plants of the genus Sagina having small spherical flowers resembling pearls