Clark was a part of the second class to graduate from Smith College in 1880 and she conceived the idea of publishing a card index of new genera and species of American plants, which was continued at the Gray Herbarium.

In the fall of 1876 she began attending Smith College and earned her Bachelor of Arts in 1880.

[1] After graduation, she taught until 1888 when she began attending Columbia College in New York City for library science.

[1] After graduation, Clark became the assistant librarian at the Gray Herbarium at Harvard University.

Clark was the main organizer of the index until 1903 when she turned it over to Mary Anna Day at the Gray Herbarium with 27,999 cards.