After graduating, Boissevain attended a lecture on botany by Hugo de Vries, which sparked her interest in the subject.

After graduating, she moved to Zürich to do further research on Dentalium species and at age 25 attained the title of doctor.

Four mollusk taxa are named after her: the species Cadulus boissevaini, Antalis boissevainae, Fustiaria Mariae and the genus Boissevainia.

When she returned to the Netherlands, she visited Aletta Jacobs to talk about the Dutch women's rights movement.

[1] Together with Rosa Manus, who she had gone to school with, she founded a commission for propaganda within the Vereeniging voor Vrouwenkiesrecht and was its president until 1912.