The spermatozoid of Lycopodiella lateralis (R. Br.) B. Øllgaard is ovoid and biflagellated and contains little cytoplasm. A large, rounded, condensed nucleus occupies the central region of the cell. At the rear of the cell is a cluster of starch-containing plastids associated with numerous elongated mitochondria and small pockets of remnant cytoplasm. The multilayered structure coils laterally around the cell anterior for just over one revolution. An anterior mitochondrion underlies the multilayered structure over its entire length and several smaller mitochondria line the inner anterior coil. Some 150 spline microtubules extend from the multilayered structure and coil posteriorly at approximately a 45° angle to the longitudinal axis of the cell. Microtubules progressively increase in length from the margins of the multilayered structure to the center and thus only a central core of approximately 30 microtubules encircles the organelles at the base of the cell. The two basal bodies are parallel and staggered in their position over the multilayered structure and are separated by about 80° around the circumference of the cell anterior. The flagella emerge in parallel and coil for nearly two revolutions. Comparisons among Lycopodiella, Palhinhaea, and Lycopodium provide the basis for evolutionary inferences associated with modifications in spermatozoid structure such as changes in cell size, whole cell coiling, and distance between basal bodies. Phylogenetic analysis of male gametogenesis suggests that Lycopodiella is part of a monophyletic lycopsid assemblage near the base of the vascular plants. Within this clade, Lycopodiella is most closely related to Palhinhaea, with Lycopodium, Phylloglossum, and Selaginella forming a sister clade. Key words: Lycopodiella, Lycopodium, spermatozoid, land plant phylogeny, locomotory apparatus, ultrastructure.

Botrychium dissectum is a homosporous fern with bisexual, subterranean gametophytes. Because of these features, B. dissectum would be suspected of displaying a very high frequency of self‐fertilization. Sporophytes collected from three populations of this species were assayed for heterozygosity by determining the electrophoretic mobility patterns displayed by two polymorphic enzymes. Extreme deviations from Hardy‐Weinberg expectations were observed in each population and analyzed by means of F‐statistics. The average inbreeding coefficient was found to be 0.951. A population genetic model is derived that demonstrates that the rate of intragametophytic self‐fertilization in homosporous ferns is equal to the inbreeding coefficient calculated from deviations from Hardy‐Weinberg expectations. It is therefore concluded that B. dissectum outcrosses about 5% of the time.

A new method of inducing apogamy in normal fern gametophytes of Pteridium aquilinum has been demonstrated. Entire plants, apparently isolated sporophytic members, and structures of an intermediate nature between sporophyte and gametophyte were produced. The method involved growing gametophytes in sterile culture on a nutrient medium containing a suitable concentration of glucose. A series of experiments was carried out in which the concentration of glucose was varied from 0–8% and the optimum concentration was established to be 2.5%. Prothalli grown in the absence of glucose, which have only their photosynthate as an energy source, produced no apogamous structures. It was found that sucrose, maltose, or fructose could be substituted for the glucose in the induction of apogamy. Four other strains of Pteridium, and strains of Osmunda cinnamomea and Adiantum pedatum, also responded to the sugar treatment by producing apogamous plants. The osmotic pressure of the medium has been shown to have no effect on the induction of apogamy but it does appear to cause the decline in the response at the higher concentrations of sugar. The role of the sugar would therefore seem to be as a respiratory substrate, which in some way favors the induction of apogamy.

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