Grindelia robusta vs tarweed

Grindelia robusta and tarweed both are nouns.

Word	Noun	Adjective	Verb	Adverb
Grindelia robusta	Yes	No	No	No
tarweed	Yes	No	No	No

As nouns, tarweed is a hypernym of Grindelia robusta; that is, tarweed is a word with a broader meaning than Grindelia robusta:

Grindelia robusta: perennial gumweed of California and Baja California
tarweed: any of various western American plants of the genus Grindelia having resinous leaves and stems formerly used medicinally; often poisonous to livestock

Other hypernyms of Grindelia robusta include gum plant, gumweed, rosinweed.

Grindelia robusta (noun)	tarweed (noun)
perennial gumweed of California and Baja California	any of various resinous glandular plants of the genus Madia; of western North and South America
	any of various western American plants of the genus Grindelia having resinous leaves and stems formerly used medicinally; often poisonous to livestock