Culver's root vs Culvers root

Culver's root and Culvers root both are nouns.

Word	Noun	Adjective	Verb	Adverb
Culver's root	Yes	No	No	No
Culvers root	Yes	No	No	No

As nouns, Culver's root and Culvers root are synonyms defined as:

Culver's root and Culvers root: a tall perennial herb having spikes of small white or purple flowers; common in eastern North America

Other synonyms of Culver's root include Culver's physic, Culvers physic, Veronicastrum virginicum, whorlywort.

Culver's root (noun)	Culvers root (noun)
a tall perennial herb having spikes of small white or purple flowers; common in eastern North America	a tall perennial herb having spikes of small white or purple flowers; common in eastern North America