SPORE GERMINATION IN THE PSILOTACEAE

Spores of several species of Psilotum and Tmesipteris were sown on a nutrient medium containing minerals and 0.2% glucose. The nutrient medium contained ammonium as the nitrogen source and lacked nitrate. From 52 to 98% of the spores of P. nudum, P. complanatum, T. lanceolata, and T. sigmatifolia germinated after 6 months in the dark. Haploid spores of P. nudum began germinating in less than 2 months; however spores of the two Tmesipteris species reached 50% germination sooner than those of the Psilotum species. Spores of T. tannensis never germinated and those of T. elongata and P. x intermedium rarely germinated (<0.1%) and never formed mature gametophytes. Spores from only one species, T. lanceolata, occasionally germinated in the light, but gametophytic development never proceeded beyond the two-celled stage. Spores of T. lanceolata and T. sigmatifolia stored at -70 degrees C for 21 months germinated essentially as well as the fresh spores. The nutrient medium appears suitable for studies on gametophytes of the Psilotaceae because it promoted spore germination and gametophytic growth for most of the species tested.