The development of the ligule ofSelaginella kraussiana is described, from the initial meristematic state to the final stages of senescence, with particular reference to the central cells. The mature ligule consists of three zones. Cells in the central zone become differentiated, with the formation of well developed endoplasmic reticulum and Golgi systems. Unusual features include the presence of agranal plastids with well developed internal tubule systems, and complex lomasomes. Many Golgi vesicles are produced, and accumulate in the groundplasm. Some of these pass into cell vacuoles (where breakdown occurs), others fuse with the plasmalemma (where discharge of contents to the outside may take place). Fine structural comparison with other secretory cells suggests that the ligule cells ofSelaginella kraussiana are not involved in the mass secretion of mucilage.