groundsel tree vs shrub

groundsel tree and shrub both are nouns.

Word	Noun	Adjective	Verb	Adverb
groundsel tree	Yes	No	No	No
shrub	Yes	No	No	No

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

groundsel tree: a shrub of salt marshes of eastern and south central North America and West Indies; fruit is surrounded with white plumelike hairy tufts
shrub: a low woody perennial plant usually having several major stems

Other hypernyms of groundsel tree include bush.

groundsel tree (noun)	shrub (noun)
a shrub of salt marshes of eastern and south central North America and West Indies; fruit is surrounded with white plumelike hairy tufts	a low woody perennial plant usually having several major stems