Abstract
Gametophytes of the fern Anemia phyllitidis respond to seven different gibberellins (A1, A3; A4, A5, A7, A8, and A9) by forming antheridia. Gibberellin A7 is active at concentrations as low as 5 X 10-10 g/ ml. Species from two of the three other genera in the family Schizaeaceae respond similarly to gibberellin A3. In contrast, nearly 40 species from 7 other families of ferns do not develop antheridia when supplied with gibberellin.