The Ceratopteris genus is a model plant system in allowing the study of life and reproductive cycles of spores, allowing for spore to gamete cellular and physical observation. The triangle water fern, Ceratopteris richardii, provided for visual identification of this transition. Spores of different densities were inoculated, cultured, and observed in germination and sexual expression. We estimated higher spore densities increase percentages of sexually expressed gametes, male and hermaphrodite; and concluded that spore density has a direct effect on germination and sexual expression numbers. The ability to observe the spore to gamete transition leads to opportunity in manipulation of gametes for biological studies related to vascular plants.
The model use of the homosporous Ceratopteris richardii (C-Fern) provides for high accessibility and understanding of its life and reproductive cycles, both haploid and diploid (2, 3.) The life and reproductive cycles of the sporophyte are easily observable under a compound microscope; and volume harvesting and culturing of spores for experimental studies are relatively easy due to the quick life cycle of the Ceratopteris at 120 days or less (4.) Spore life and reproductive cycle summary consists of spore germination, gametophyte differentiation, pheromone antheridiogen sexual differentiation, embryonic development, through to spore maturation (Fig. 1.) Male or hermaphrodite gametes, of the Ceratopteris, are determined by the pheromone antheridiogen or ACE. This pheromone is responsible for stimulating the determination of male gametes and is secreted from the hermaphrodite gametes. This allows for a ratio of males to hermaphrodite gametes to vary depending on the spore density (Fig 3, 4) (5.) We estimated that higher spore densities will generate...