Mosses, liverworts, and hornworts form a group commonly referred to as bryophytes. Specialists at the Garden explore remote regions to study bryophytes of China, Central America, Andean South America, Central Asia, Africa, and Madagascar.

The Garden's herbarium collection of more than 320,000 bryophytes is one of the world's largest and increases by some 14,000 specimens each year. The Bryology Department uses TROPICOS to compile the Index of Mosses and Recent Literature on Bryophytes and recently produced a worldwide Checklist of Mosses.