French weed vs pennycress

French weed and pennycress both are nouns.

Word	Noun	Adjective	Verb	Adverb
French weed	Yes	No	No	No
pennycress	Yes	No	No	No

As nouns, pennycress is a hypernym of French weed; that is, pennycress is a word with a broader meaning than French weed:

French weed: foetid Eurasian weed having round flat pods; naturalized throughout North America
pennycress: any of several plants of the genus Thlaspi

French weed (noun)	pennycress (noun)
foetid Eurasian weed having round flat pods; naturalized throughout North America	any of several plants of the genus Thlaspi