Mary Strong Clemens (3 January 1873 – 13 April 1968) was an American botanist and plant collector.
Born in New York as Mary Knapp Strong, she married Joseph Clemens, a Methodist Episcopalian minister, in 1892.
A fanatical botanist, she collected plants assiduously throughout her long life, in the remote parts of the Philippines, Borneo, China, New Guinea and Australia.
The latter part of her life was spent in Australia, where she died in Brisbane, Queensland.