Conditions for Germination of Spores of Onoclea sensibilis

Abstract

1. These experiments deal with the conditions for germination of spores of Onoclea sensibilis. 2. Spores germinate best in diffused light, and intense diffused light is better than moderate or weak. 3. Sunlight is unfavorable to germination, and intense, long continued sunlight destroys chlorophyll. 4. Spores germinate in absolute darkness. 5. The highest percentage of germination in continuous light was obtained at 31⚬ C. 6. The minimum temperature for germination in intense diffused light is 16⚬, the optimum 28⚬, and the maximum 34⚬; 40⚬ kills the spores. 7. The minimum temperature for germination in absolute darkness is 24⚬, the optimum 28⚬-29⚬, and the maximum 33⚬. 8. The less refrangible rays of the spectrum are the most effective in causing germination, whether intermittent or continuous. 9. Viability in light and darkness depends upon age of spores. Spores retain the ability to germinate in light longer than the ability to germinate in the dark. 10. Old spores differ from fresh ones in that they contain less chlorophyll, and the fat is present in more conspicuous globules. 11. Since O. sensibilis spores germinate over a wide range of light and temperature intensities, but lose their viability in a comparatively short time, it is suggested that age may be the limiting factor. 12. It is suggested that the conflicting accounts of previous investigators have been caused by some undescribed conditions of experimentation, such as variations in temperature, light intensity, types of media, or age of spores.