APICAL CONTROL OF GROWTH IN A FILAMENTOUS RED ALGA (CERAMIACEAE, RHODOPHYTA)

The undescribed ceramiacean red alga used in this work is closely rela ted to Ceramium. The alga is pseudodichotomously branched with alterna te axes being dominant. Removal of the apical tip from the primary ind eterminate axis increased the production of adventitious branches from pericentral cells behind the apex. This effect was not reversed with the addition of exogenous IAA to the growth medium in a concentration range of 10(-9) M to 10(-4) M. Removal of the apical tip from the subo rdinate axis did not influence adventitious branch production.