Dirca palustris vs shrub

Dirca palustris and shrub both are nouns.

Word	Noun	Adjective	Verb	Adverb
Dirca palustris	Yes	No	No	No
shrub	Yes	No	No	No

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

Dirca palustris: deciduous shrub of eastern North America having tough flexible branches and pliable bark and small yellow flowers
shrub: a low woody perennial plant usually having several major stems

Other hypernyms of Dirca palustris include bush.

Dirca palustris (noun)	shrub (noun)
deciduous shrub of eastern North America having tough flexible branches and pliable bark and small yellow flowers	a low woody perennial plant usually having several major stems