hardstemmed bulrush vs sedge

hardstemmed bulrush and sedge both are nouns.

Word	Noun	Adjective	Verb	Adverb
hardstemmed bulrush	Yes	No	No	No
sedge	Yes	No	No	No

As nouns, sedge is a hypernym of hardstemmed bulrush; that is, sedge is a word with a broader meaning than hardstemmed bulrush:

hardstemmed bulrush: widely distributed North American sedge having rigid olive green stems
sedge: grasslike or rushlike plant growing in wet places having solid stems, narrow grasslike leaves and spikelets of inconspicuous flowers

hardstemmed bulrush (noun)	sedge (noun)
widely distributed North American sedge having rigid olive green stems	grasslike or rushlike plant growing in wet places having solid stems, narrow grasslike leaves and spikelets of inconspicuous flowers