The effect of spore density on germination and development in Pteridium, monitored using a novel culture technique

Percentage germination and percentage transition to two-dimensional growth in Pteridium (bracken fern) were recorded for spores sown on a solid Phytag el(TM)-based growth medium at known densities of between 3 and 9883 spores mm(-2). The maximum germination recorded occurred at sowing densities highe r than those at which maximum transition occurred. Percentage germination w as greatest (43 to 52% of spores sown) at intermediate densities (187 to 21 14 spores mm(-2)), being highest (52% of spores sown) at 360 spores mm(-2). Percentage transition was highest at the lowest densities used. It was con cluded that germination and transition have different density optima and th at investigations of these two phenomena in ferns should take account of th is.