Classified Information

Domain: Eukaryota

Kingdom: Plantae

Phylum: Tracheophyta   

Class: Magnoliopsida

Order: Asterales     

Family: Asteraceae

Genus: Helianthus   

Species: Helianthus annuus

Domain Eukaryota: multicellular organism with amembrane bound nucleus and other specialized organelles within the cytoplasm.

Kingdom Plantae: photosynthetic, can conduct sexual reproduction with an alternation of generations between gametophyte and sporophyte.

Phylum Tracheophyta: water conducting cells, called tracheids, to conduct water throughout the plant and that show spiral bands in walls.

Class Magnoliopsida: a dicotelydon: vascular bundles in ring formation, veins on leaves branch, flowers come in multiples of 4 or 5.

Order Asterales: leaves alternate, the anthers are united into a tube, flowers are collected into heads surrounded by bracts, is filament free, no stipules. 

Family Asteraceae (Compositae*): leaves alternate and have no stipules, flowers in compact heads with 5 stamens, the heads often appear as the flowers when actually some have ray flowers and small tube flowers in central disk, under each flower head is a small grouping of leaflets, known as bracts. (*The family was formerly known as compositae, but it recently changed because it did not end in -aceae like all other plant families.  Also, when classifying there is a representative genus within the family, however there was no Composita genus in the Compositae, but there was an Aster, hence Asteraecae)

Genus Helianthus: ray flowers are pointed, brown or yellow centers, falling when seed matures, the lower leaves are opposite, stems are erect, heads usually radiate.

Species Helianthus annuus: leaves and stems are green, stems usually erect, usually taproots, disk usually over two inches broad, leaves mostly alternate, head radiates, several heads in a branched cluster.

For another layout of the classification information, as well as closely related organisms visit the Phylogenetic Tree.

For even further breakdown of why the sunflower belongs to each category visit the Taxonomy of Helianthus annuus.