Leonotis leonurus vs herb

Leonotis leonurus and herb both are nouns.

Word	Noun	Adjective	Verb	Adverb
Leonotis leonurus	Yes	No	No	No
herb	Yes	No	No	No

As nouns, herb is a hypernym of Leonotis leonurus; that is, herb is a word with a broader meaning than Leonotis leonurus:

Leonotis leonurus: relatively nontoxic South African herb smoked like tobacco
herb: a plant lacking a permanent woody stem; many are flowering garden plants or potherbs; some having medicinal properties; some are pests

Other hypernyms of Leonotis leonurus include herbaceous plant.

Leonotis leonurus (noun)	herb (noun)
relatively nontoxic South African herb smoked like tobacco	aromatic potherb used in cookery for its savory qualities
	a plant lacking a permanent woody stem; many are flowering garden plants or potherbs; some having medicinal properties; some are pests