[1] Calder was interested in biological and chemical sciences, and at the age of 18, she entered the University of Glasgow to study botany.

She abandoned her earlier paper on tomatoes and began work on a catalogue of the large collection of coal ball slides by the Scottish paleobotanist Robert Kidston.

In 1935, she published a paper on petrified pteridosperms (seed ferns) using the revolutionary cellulose peel techniques developed by Walton in 1928.

Unlike previous techniques which used thin sections of rock, the cellulose peel method allowed more detail of the fossils to be preserved.

[1] In 1938, Calder worked on the seed plants Calymmatotheca kidstonii and Samaropsis scotica, both from the Tournaisian age (345.3 to 359.2 million years ago) of the Lower Carboniferous (Mississippian).

She published one more paper in 1953 on Araucaria mirabilis, Araucarites sanctaecrucis, and Pararaucaria patagonica; all of which are araucarian conifers from the Middle Jurassic petrified forests of Argentina.