American bryologist and wife of N.L. Britton, the first director of the New York Botanical Garden. E.G. Britton devoted 30 years of her life to the study of mosses and played a key role in the founding of the New York Botanical Garden.

Born in New York City, Elizabeth Britton (née Knight) spent her early childhood at her grandfather's sugar plantation in Matanzas, Cuba, where she became interested in plants and picked up a degree of Spanish that would later be of use during expeditions. She graduated from, then taught critic and natural sciences at the Normal College (now Hunter College) in New York, from 1875 to 1885, when she married Nathanial Lord Britton. Both were keen botanists and members of the Torrey Botanical Club. E.G. Britton had been a member since 1879, when she shared with other members her recent discovery of a rare curly grass fern, Schizaea pusilla, in Nova Scotia. She served as the club's curator of mosses from 1884 to 1885 and the editor of its memoirs from 1886 to 1888. One of the leading botanists of the day, she was the only female charter member of the Botanical Society of America, founded in 1893. She also took on unofficial curatorship of the moss herbarium at Columbia College, where her husband taught geology, helping it to acquire the highly significant moss collection of Swiss bryologist August Jaeger.

In 1888 the Brittons sailed to England to examine the Bolivian collection of H.H. Rusby at Kew. E.G. Britton wrote An Enumeration of the Plants Collected by H.H. Rusby, in Bolivia, 1885-1886 published in the Memoirs of the Torrey Botanical Club. However, the most significant result of the visit to Kew was its inspiring the couple to establish a similar institution in New York. Indeed it was Mrs Britton who suggested it to her husband, and thus she began driving the fundraising that led to the creation of the New York Botanical Garden in the 1890s, with N.L. Britton as Director. E.G. Britton worked, unpaid, from 1912 as its Honorary Curator of Mosses, in which role her accomplishments included reorganising its acquisition, the William Mitten moss herbarium. She was also a fervent field worker, making extensive collections in the Adirondack and Appalachian Mountains, Puerto Rico, Cuba and Jamaica. The Brittons together carried out 16 expeditions to Puerto Rico between 1906 and 1933, collecting more than 10,000 specimens and discovering many new species. They were also influential in the establishment of a forestry policy for the island.

During her lifetime, E.G. Britton compiled a considerable amount of scientific work, numbering 346 publications on mosses, ferns and wildflowers. She especially turned her attention towards the latter from the 1900s, setting up with cohorts the Wildflower Preservation Society and campaigning for the conservation of native flora. She was also active in the Sullivant Moss Society, later known as the American Bryological Society, and wrote for the (short-lived) popular scientific publication, The Observer. For this popular series on mosses, Britton dreamed up fanciful titles such as 'The Humpbacked Elves' and 'The Brownies'. The Elizabeth Gertrude Britton Moss Herbarium of the New York Botanical Garden was named after her. The bryophyte genus Bryobrittonia R.S. Williams was also named in her honour. Bryophyte material deposited at K was transferred to BM (c. 1961) under the Morton Agreement.