kingcup vs swamp plant

kingcup and swamp plant both are nouns.

Word	Noun	Adjective	Verb	Adverb
kingcup	Yes	No	No	No
swamp plant	Yes	No	No	No

As nouns, swamp plant is a hypernym of kingcup; that is, swamp plant is a word with a broader meaning than kingcup:

kingcup: swamp plant of Europe and North America having bright yellow flowers resembling buttercups
swamp plant: a semiaquatic plant that grows in soft wet land; most are monocots: sedge, sphagnum, grasses, cattails, etc; possibly heath

Other hypernyms of kingcup include bog plant, marsh plant.

kingcup (noun)	swamp plant (noun)
any of various plants of the genus Ranunculus	a semiaquatic plant that grows in soft wet land; most are monocots: sedge, sphagnum, grasses, cattails, etc; possibly heath
swamp plant of Europe and North America having bright yellow flowers resembling buttercups