dragonhead vs dragon's head

dragonhead and dragon's head both are nouns.

Word	Noun	Adjective	Verb	Adverb
dragonhead	Yes	No	No	No
dragon's head	Yes	No	No	No

As nouns, dragonhead and dragon's head are synonyms defined as:

dragonhead and dragon's head: American herb having sharply serrate lanceolate leaves and spikes of blue to violet flowers

Other synonyms of dragonhead include Dracocephalum parviflorum.

dragonhead (noun)	dragon's head (noun)
American herb having sharply serrate lanceolate leaves and spikes of blue to violet flowers	American herb having sharply serrate lanceolate leaves and spikes of blue to violet flowers