poisonous plant vs flora

poisonous plant and flora both are nouns.

Word	Noun	Adjective	Verb	Adverb
poisonous plant	Yes	No	No	No
flora	Yes	No	No	No

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

poisonous plant: a plant that when touched or ingested in sufficient quantity can be harmful or fatal to an organism
flora: (botany) a living organism lacking the power of locomotion

Other hypernyms of poisonous plant include plant, plant life.

poisonous plant (noun)	flora (noun)
a plant that when touched or ingested in sufficient quantity can be harmful or fatal to an organism	(botany) a living organism lacking the power of locomotion
	all the plant life in a particular region or period