After earning a Ph.D. in botany and becoming the first full-time female professor at Northwestern, she went on a number of international scientific expeditions to Central America in order to collect plant specimens and find new species.

[5] Carlson's botany research starting from 1927 focused on the development of orchids, including discovering ways to grow them in varied climates.

[8] Carlson announced in October 1936 that she had succeeded in figuring out the cultivation method for the grass pink orchid, reducing its germination to flowering time period to only three years, and would have cheap seeds and bulbs available for the public soon after.

[9][10] As a practicing botanist, Carlson made frequent trips to Mexico and Central America to search and catalog plant species in the regions.

In a 1940 paper, Carlson described the first finding of a special type of seed coat found only in a few orchid species and surrounding the plant embryo.

[15] Two years later beginning in December 1948 and extending into 1949, the pair conducted another trip, but without travel by plane or train, but by car for the entire trek.

Another purpose was to replace the White Nun orchid obtained in the 1946 trip, as many of the specimens from that time had been accidentally destroyed after a power failure in the university greenhouse during the middle of winter.

Five new species of ferns were catalogued there, along with an investigation into several mining sites along the route to look for fossilized plants at the request of botanists at the Field Museum.

Carlson traced the origins of the plant throughout Mexico, focusing particularly on a canyon near Iguala where Russelia pringlei had been identified and named by Cyrus Pringle in 1906.

[20] Carlson would make numerous international trips throughout her career, involving the countries of Costa Rica, El Salvador, Guatemala, Honduras, and Mexico.

[4] She retired in 1958 from being an active professor at Northwestern University, but remained working as a research assistant at the Field Museum and continued conducting collecting expeditions, primarily in Mexico.