Its core subject and collection focus is medicinal plants, with emphasis on botany, pharmacy, natural history, alternative medicine, and the history of medicine and science.

The collections focus on botany, mycology, pharmacy, herbal medicine, chemistry, natural history, horticulture, and the history of medicine and science.

The Lloyd also holds material on alchemy, evolution, ecology, ethnobotany, midwifery, entomology, ornithology, agriculture, exploration and travel, and the science of food and cooking.

The print collections consist of monographs, serials, reference resources, and rare books dating back to 1493; the archives collections chronicle the work of botanists, pharmacognosists, pharmacists, illustrators, artists, and allied organizations.

Other formats collected include photographs and slides, medicinal and pharmaceutical artifacts, and artwork.