marsh tea vs shrub

marsh tea and shrub both are nouns.

Word	Noun	Adjective	Verb	Adverb
marsh tea	Yes	No	No	No
shrub	Yes	No	No	No

As nouns, shrub is a hypernym of marsh tea; that is, shrub is a word with a broader meaning than marsh tea:

marsh tea: bog shrub of northern and central Europe and eastern Siberia to Korea and Japan
shrub: a low woody perennial plant usually having several major stems

Other hypernyms of marsh tea include bush.

marsh tea (noun)	shrub (noun)
bog shrub of northern and central Europe and eastern Siberia to Korea and Japan	a low woody perennial plant usually having several major stems