SPORE GERMINATION IN THE PSILOTACEAE

Spores of several species of Psilotum and Tmesipteris were sown on a n utrient medium containing minerals and 0.2% glucose. The nutrient medi um contained ammonium as the nitrogen source and lacked nitrate. From 52 to 98% of the spores of P. nudum, P. complanatum, T. lanceolata, an d T. sigmatifolia germinated after 6 months in the dark. Haploid spore s of P. nudum began germinating in less than 2 months; however spores of the two Tmesipteris species reached 50% germination sooner than tho se of the Psilotum species. Spores of T. tannensis never germinated an d 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 de velopment never proceeded beyond the two-celled stage. Spores of T. la nceolata and T. sigmatifolia stored at -70 degrees C for 21 months ger minated essentially as well as the fresh spores. The nutrient medium a ppears suitable for studies on gametophytes of the Psilotaceae because it promoted spore germination and gametophytic growth for most of the species tested.