EFFECTS OF RED AND FAR-RED ILLUMINATION ON THE ELONGATION OF FERN PROTONEMATA AND RHIZOIDS

The elongation of fern protonemata is controlled by red andfar-red light in an atypical fashion. Red light promotes theelongation of young plants but inhibits the elongation of olderplants. Far-red light promotes elongation regardless of filamentage, and the maximum promotion by far-red is greater than thepromotion which red light causes in young filaments. The elongationof rhizoids is under typical red, far-red control. Red lightpromotes elongation, and a period of far-red illumination followingred light treatment negates the promotive effects of red light. ¹ Present address of the authors: Dept. of Bacteriology andBotany, Syracuse University, Syracuse, New York, U. S. A. (Received November 5, 1962; )