gumweed vs gum plant

gumweed and gum plant both are nouns.

Word	Noun	Adjective	Verb	Adverb
gumweed	Yes	No	No	No
gum plant	Yes	No	No	No

As nouns, gumweed and gum plant are synonyms defined as:

gumweed and gum plant: any of various western American plants of the genus Grindelia having resinous leaves and stems formerly used medicinally; often poisonous to livestock

Other synonyms of gumweed include rosinweed, tarweed.

gumweed (noun)	gum plant (noun)
any of various western American plants of the genus Grindelia having resinous leaves and stems formerly used medicinally; often poisonous to livestock	any of various western American plants of the genus Grindelia having resinous leaves and stems formerly used medicinally; often poisonous to livestock