Experimental and Analytical Studies of Pteridophytes: XXI. Sterile cultures of an abnormal growth from the gametophyte of bracken

The isolation and growth in sterile culture through sixteenpassages, each of 4 to 6 weeks' duration, of an abnormal growthisolated from a gametophyte of Pteridium aquilinum var. latiusculumis reported, and the nutritional requirements described. The cultures consist of green, photosynthetic, predominantlyfilamentous, but coherent, masses. Prothalli were regeneratedon five occasions during the first two passages only. Outgrowthsof whitish or pale green parenchymatoua tissue occur. Thesepossess a central strand of elongated cells, some of which becomedifferentiated into a core of tracheides. Prothalli of the strain in culture are haploid. When examinedsoon after the initial explantation, the filamentous parts ofthe cultures were diploid, but there has been a subsequent increasein the number of chromosomes, and each cell is now irregularlyaneuploid, with a chromosome number between triploid and tetraploid.