sea dahlia vs tickweed

sea dahlia and tickweed both are nouns.

Word	Noun	Adjective	Verb	Adverb
sea dahlia	Yes	No	No	No
tickweed	Yes	No	No	No

As nouns, tickweed is a hypernym of sea dahlia; that is, tickweed is a word with a broader meaning than sea dahlia:

sea dahlia: stout herb with flowers one to a stalk; ornamental developed from a Mexican wildflower
tickweed: any of numerous plants of the genus Coreopsis having a profusion of showy usually yellow daisylike flowers over long periods; North and South America

Other hypernyms of sea dahlia include coreopsis, tick-weed, tickseed.

sea dahlia (noun)	tickweed (noun)
stout herb with flowers one to a stalk; ornamental developed from a Mexican wildflower	any of numerous plants of the genus Coreopsis having a profusion of showy usually yellow daisylike flowers over long periods; North and South America