wild oats vs cornflower

wild oats and cornflower both are nouns.

Word	Noun	Adjective	Verb	Adverb
wild oats	Yes	No	No	No
cornflower	Yes	No	No	No

As nouns, cornflower is a hyponym of wild oats; that is, cornflower is a word with a more specific, narrower meaning than wild oats:

wild oats: any of various plants of the genus Uvularia having yellowish drooping bell-shaped flowers
cornflower: plant of southern and southeastern United States grown for its yellow flowers that can be dried

Other hyponyms of wild oats include strawflower, Uvularia grandiflora.

wild oats (noun)	cornflower (noun)
any of various plants of the genus Uvularia having yellowish drooping bell-shaped flowers	an annual Eurasian plant cultivated in North America having showy heads of blue or purple or pink or white flowers
	plant of southern and southeastern United States grown for its yellow flowers that can be dried