By using aseptic culture methods it has proved possible to study the roles of leaves and roots in the control of inflorescence initiation and development in Carex. Removal of leaves upsets initiation and growth of the inflorescence and it is concluded that the continued stimuli from the leaves essential for normal development are not supplied by leaves appreciably less than half grown. Removal of roots or root apices upsets inflorescence initiation and branching. It is probable that a stimulus from the roots promotes initiation but is not essential, whereas a factor produced by actively growing roots is essential for normal branching to occur. The only substance tested which could alter the degree of branching was benzyladenine. On the evidence available it is suggested that normal branching of the inflorescence may depend on an adequate supply of cytokinin from the roots.