Mary Knapp Strong Clemens (January 3, 1873 - April 13, 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. Her husband joined the US Army in 1902 as a chaplain, and served in the Philippines, America, and then France during the First World War, retiring in 1918. During the period spent in the Philippines in 1905-1907, she made extensive trips through Luzon and Mindanao. After her husband's retirement, he became her assistant and the couple worked as a team of professional, full-time botanical collectors. Mary collected the plants while Joseph dried them and prepared them for shipment. Between the First and Second World Wars the Clemenses visited China, Indo-China, British North Borneo, Sarawak, Java and Singapore. In August 1935 they went to the Mandated Territory of New Guinea where Joseph died in January 1936 of food poisoning from contaminated wild boar meat. Mary continued to work in New Guinea until December 1941 when she was compulsorily evacuated to Australia because of impending war. She was allocated some space at the Queensland Herbarium. A broken hip in 1950 marked the end of extended field trips but she continued to work at the Queensland Herbarium until the early 1960s. She died peacefully in 1968 at the age of 95.