Sium suave vs bog plant

Sium suave and bog plant both are nouns.

Word	Noun	Adjective	Verb	Adverb
Sium suave	Yes	No	No	No
bog plant	Yes	No	No	No

As nouns, bog plant is a hypernym of Sium suave; that is, bog plant is a word with a broader meaning than Sium suave:

Sium suave: stout white-flowered perennial found wild in shallow fresh water; northern United States and Asia
bog plant: a semiaquatic plant that grows in soft wet land; most are monocots: sedge, sphagnum, grasses, cattails, etc; possibly heath

Other hypernyms of Sium suave include marsh plant, swamp plant.

Sium suave (noun)	bog plant (noun)
stout white-flowered perennial found wild in shallow fresh water; northern United States and Asia	a semiaquatic plant that grows in soft wet land; most are monocots: sedge, sphagnum, grasses, cattails, etc; possibly heath