cow parsnip vs herbaceous plant

cow parsnip and herbaceous plant both are nouns.

Word	Noun	Adjective	Verb	Adverb
cow parsnip	Yes	No	No	No
herbaceous plant	Yes	No	No	No

As nouns, herbaceous plant is a hypernym of cow parsnip; that is, herbaceous plant is a word with a broader meaning than cow parsnip:

cow parsnip: tall coarse plant having thick stems and cluster of white to purple flowers
herbaceous plant: a plant lacking a permanent woody stem; many are flowering garden plants or potherbs; some having medicinal properties; some are pests

Other hypernyms of cow parsnip include herb.

cow parsnip (noun)	herbaceous plant (noun)
tall coarse plant having thick stems and cluster of white to purple flowers	a plant lacking a permanent woody stem; many are flowering garden plants or potherbs; some having medicinal properties; some are pests