Sium vs genus Sium

Sium and genus Sium both are nouns.

Word	Noun	Adjective	Verb	Adverb
Sium	Yes	No	No	No
genus Sium	Yes	No	No	No

As nouns, Sium and genus Sium are synonyms defined as:

Sium and genus Sium: perennial of wet and marshy places in the Northern Hemisphere: water parsnips

Sium (noun)	genus Sium (noun)
perennial of wet and marshy places in the Northern Hemisphere: water parsnips	perennial of wet and marshy places in the Northern Hemisphere: water parsnips