The purple lilac, Syringa vulgaris, is the state flower of New Hampshire.
New Hampshire historian Leon Anderson writes in To This Day that the purple lilac was first imported from England and planted at the Portsmouth home of Governor Benning Wentworth in 1750. It was adopted as our state’s flower in 1919. That year bills and amendments were introduced promoting the apple blossom, purple aster, wood lily, Mayflower, goldenrod, wild pasture rose, evening primrose and buttercup as the state flower. A long and lively debate followed regarding the relative merits of each flower. The purple lilac was ultimately chosen, according to Anderson in New Hampshire’s Flower -- Tree -- Bird because it "is symbolic of that hardy character of the men and women of the Granite State."
New Hampshire Revised Statute Annotated (RSA) 3:5; Anderson, Leon. Flower -- Tree -- Bird
The pink lady’s slipper, Cypripedium acaule, is hereby designated as the official state wildflower of New Hampshire.
In 1991, the Pink Lady’s Slipper became the state’s wildflower. The plant is native to New Hampshire and grows in the moist wooded areas of the state.
Sources: New Hampshire Revised Statute Annotated (RSA) 3:17; Anderson, Leon. Flower -- Tree -- Bird
The New Hampshire Almanac is compiled by the New Hampshire State Library from state statutes and other sources as noted.
NH.gov - The Official Web Portal of the State of New Hampshire