Field and laboratory experiments were conducted with unicorn-plant to determine conditions required for germination and to measure seed production. Field-grown plants produced an average of 122 pods/plant with an average of 71 seed/pod. The highest percent germination from seed harvested in 1980 occurred following a 2-week prechill treatment of 4 C. Germination increase was greater by removing the seed coat and the membrane enclosing the embryo than by removing the seed coat alone. Germination of seed from all pod compartments was similar. Aqueous extracts of unicorn-plant testa, leaf, stem, root, and exocarp were inhibitory in petri dish bioassays to cotton radicle growth. Extracts of stem, root, and exocarp were inhibitory to wheat radicle growth, and extracts of endocarp, leaf, and exocarp were inhibitory to unicorn-plant radicle growth. Seed buried in the field 10 cm deep for 1 to 8 months showed increased germination over time. Germination was lower when seed were stored at 4 C for 1 to 8 months in a soil having 25% (v/v) water.