The Maryland State Flower since 1918. A daisylike biennial plant native to North America, east of the Rocky Mountains, it migrated from the western prairies in hay shipped to the east. Rubeckia hirta was first described by the Swedish naturalist Linnaeus in his Species Plantarum (1753). Linnaeus named the plant for two professors at the University of Uppsala, a father and son both named Olav Rudbeck. Hirta means "rough hairy" in botanical Latin and it refers to the hairy stems and leaves of the plant.

The plant grows 2-3 feet high and blooms in summer (May to October, depending on location). The disk shaped flowers are 2-3 inches across; long yellow petals radiate from a dark purple-brown conical center that holds the seeds. Besides the hairy stems, the leaves are hairy and serrated. The Black-eyed Susan is a member of the family Asteraceae (commonly called Compositae), the order Asterales, class Magnaliopsida and division Magnoliophyta. It is a relative of the sunflower.

Sources:
Plant Taxonomy by Lyman Benson. Ronald Press Company, New York, 1962
Vascular Plant Families by James Payne Smith, Jr. Mad River Press, Inc., Eureka, CA, 1977
State Flowers by Anne Ophelia Dowden. Thomas Y. Crowell, New York, 1978
The Audubon Society Field Guide to North American Wildflowers by William A. Niering and Nancy C. Olmstead. Alfred A. Knopf, New York, 1979
http://www.encyclopedia.com/articles/01531.html
http://www.mdarchives.state.md.us/msa/mdmanual/01glance/html/symbols/flower.html