subclass Hamamelidae vs Hamamelidanthum

subclass Hamamelidae and Hamamelidanthum both are nouns.

Word	Noun	Adjective	Verb	Adverb
subclass Hamamelidae	Yes	No	No	No
Hamamelidanthum	Yes	No	No	No

subclass Hamamelidae (noun)	Hamamelidanthum (noun)
a group of chiefly woody plants considered among the most primitive of angiosperms; perianth poorly developed or lacking; flowers often unisexual and often in catkins and often wind pollinated; contains 23 families including the Betulaceae and Fagaceae (includes the Amentiferae); sometimes classified as a superorder	genus of fossil plants of the Oligocene having flowers resembling those of the witch hazel; found in Baltic region