XVI International Botanical Congess

The spermatozoid of Psilotum coils 2.5 revolutions and is outlined by a parallel band of up to 180 microtubules. The elongated nucleus parallels the cellular coils with numerous mitochondria and starch-laden plastids distributed along its length. Along the anterior coil is a locomotory apparatus that consists of ca. 36 flagella inserted into the cell by basal bodies. Subtending the basal bodies is a long narrow lamellar strip with an overlying spline and an elongated anterior mitochondrion. Additional amyloplasts and mitochondria are aggregated along the anterior coil in association with the locomotory apparatus, while a fibrous ridge encircles the leading edge of the cell. These characteristics are shared with spermatozoids of ferns and lend support to the hypothesis that Psilotum nudum is a fern.