THE SPORE-GERMINATION PATTERN OF THELYPTEROID FERNS

Cell division patterns in germinating spores of several Thelypteris species were studied using light microscopy of sectioned material and scanning electron microscopy. All species exhibited the same basic germination pattern, characterized by an asymmetric cell division of the spore parallel to the equatorial plane to delimit a proximal rhizoid, followed by a perpendicular division of the basal cell to form the protonemal cell. While spore-germination patterns appear to be a potentially useful taxonomic character in some groups of ferns, the homogeneity in this character exhibited by the thelypteroid group impairs its usefulness in the taxonomy of Thelypteris.