The Hortorium is a special area adjacent to the Molawin Bridge located at the lower campus of the university. It covers a small tract of land which encompasses the junction of two streams, the Molawin and Marulas creeks which flows from the watersheds of Mt. Makiling. A small building, built in 1927 and said to be a workshed of the then UP College of Agriculture, serves as its main facility.

A “living or in-situ collection,” the Hortorium is planted to and serves as home of around 400 species of Philippine food, medicinal, tonic, and ornamental plants, some of which have been collected during museum expeditions.