[1] On August 27, 1885, she married Nathaniel Lord Britton, an assistant in geology at Columbia College who shared her growing interest in botany.

[1] She joined the Torrey Botanical Club in 1879,[1] and in 1881 she published her first scientific paper in that organization's Bulletin, reporting observations of unexpected white flowers in two species of plants.

[7] After her marriage in 1885, Britton resigned her teaching position at Normal College, and took charge of the moss collections at Columbia in an unofficial, unpaid capacity.

[4][11] She served as editor of the Bulletin of the Torrey Botanical Club from 1886 to 1888;[12] in 1889, she published the first of an eleven-part series of papers titled Contributions to American Bryology in that journal.

"[4] She worked with her husband to acquire for Columbia the moss herbarium of August Jaeger of Switzerland; Britton persuaded wealthy friends to contribute the necessary $6,000.

[5][9] Inspired by the quality and quantity of Kew's herbarium, library, and gardens, the couple set about organizing an institution of comparable stature for New York.

[23] As part of her unofficial position at Columbia, Britton acted as advisor to doctoral students, including James Franklin Collins[24] and Abel Joel Grout.

[35] Soon, tensions between field botanists (many of them women) and those with academic affiliations (many of them men), as well as disagreements over centralizing leadership on policy questions (specifically, addressing the growing number of automobiles on the road) led to its reorganization as the Wild Flower Preservation Society in 1925, with Percy L. Ricker as its head.

[36][30] Nevertheless, Britton continued to promote the cause for nearly 35 years, by publishing, lecturing, and conducting correspondence; her efforts led to adoption of legislation in various states, as well as local conservation activities in garden clubs and public schools.

The series of articles gives evidence of Britton writing in an accessible, non-technical register, such as the introduction of "Wild Pink" (Silene caroliniana): Before the trees cast much shade, while their greens are still so exquisitely fresh and varied, a bright flash of color will attract the eye to the Wild Pink, growing in hilly places on rocks or often in their cracks and crevices with the Saxifrage.

[37]In 1925, as chair of the conservation committee of the Federated Garden Clubs of New York State, Britton successfully led a boycott campaign against the common practice of harvesting wild American holly for use as a Christmas decoration.

Marshall Avery Howe described Britton as "a woman of extraordinary physical and mental energy—the possessor of a remarkably quick and brilliant intellect.

She has left an enduring record in the literature of science, and her well-directed activities have had an outstanding influence in the conservation of the native flora of the United States.

A gift of the New York Bird and Tree Club, it is mounted on a ten-ton boulder of Bronx schist, and its text reads, "Let those who find pleasure in this garden remember Elizabeth Gertrude Knight Britton, lover of wildflowers and ardent advocate of their protection".

[45] Elizabeth Britton died at her home at 2965 Decatur Avenue[46] in The Bronx on February 25, 1934, following an apoplectic stroke; her husband Nathaniel survived her for four months.

[12][20] Although she was nominally a member of the Episcopalian faith, she was buried in the Moravian Cemetery on Staten Island, where her husband's ancestors had been early settlers and he held property.