Word Study
helianthus
CIDE DICTIONARY
helianthus, n.
any plant of the genus Helianthus having large flower heads with dark disk florets and showy yellow rays. [WordNet 1.5]
OXFORD DICTIONARY
helianthus, n. any plant of the genus Helianthus, including the sunflower and Jerusalem artichoke.
Etymology
mod.L f. Gk helios sun + anthos flower
For further exploring for "helianthus" in Webster Dictionary Online