Trillium cernuum is accepted species in
the family
Melanthiaceae
subfamily:
Parideae,
Genus
Trillium 
This species is found in Connecticut, Delaware, District of Columbia, Illinois, Indiana, Iowa, Maine, Manitoba, Maryland, Massachusetts, Michigan, Minnesota, New Brunswick, New Hampshire, New Jersey, New York, Newfoundland, North Dakota, Nova Scotia, Ohio, Ontario, Pennsylvania, Prince Edward I., Québec, Rhode I., Saskatchewan, South Dakota, Vermont, Virginia, West Virginia, Wisconsin.