(from follis, "a bag.") a species of seed-vessel first mentioned by Linnaeus in his Delineatio Plantarum, generally consisting of one valve, which opens from bottom to top on one side, and has no future for fattening or attaching the seeds within it.

FOLLICULI are likewise defined by the same author to be small glandular vessels distended with air, which appear on the surface of some plants; as at the root of water-milfoil, and on the leaves of aldrovanda. In the former, the vessels in question are roundish, and furnished with an appearance like two horns; in the latter, pot-shaped, and semicircular.