Gemmation in cultured gametophytes ofOsmunda regalis.

Gametophytes ofOsmunda regalis were culturedin vitro to determine the optimal conditions for growth and development. Culture media with low ammonium concentration (Knop, Knudson or 1/4 Murashige and Skoog dilution) were the most effective for growth of this organism. Addition of sucrose and mannitol to the culture medium at the same osmoticum, inhibits or enhances, respectively, growth and development of the gametophytes, which show a strong autotrophyin vitro. In darkness, both two-dimensional growth and sexual organ formation took place. Gemmae formation is described for the first time in this species and this process does not occur without sucrose in the culture medium or in darkness.