Skinner, Donald Roy2024-08-152024-08-1519921992https://hdl.handle.net/1828/19713This study utilized four clones to trace the anatomical development of the coastal loblolly pine (Pinus taeda L.) ovule and embryo, using light microscopy. This study covered the period from the spring following initiation of the reproductive structures until cone maturity, a total of 19 months spread over two growing seasons. Particular attention was directed toward determining the time of fertilization, the number of archegonia per ovule, the number of pre-cleavage and post-cleavage embryos produced by each ovule and the time of subordinate post-cleavage embryo degeneration. In addition, these four clones plus one other clone were used to determine the number of ovuliferous scales in total and by type, the seed production capacity and seed germination of the species. Ovule and embryo development in this species deviates in only one respect from the accepted pattern in other temperate pines, this being the delay in the onset of free nuclear division, within the female gametophyte, until the start of the second growing season. Loblolly pine had one to four archegonia in each ovule. If each was fertilized (between June 6 and 13) a maximum of four pre-cleavage embryos and sixteen post-cleavage embryos could be produced. By July 28 subordinate post­-cleavage embryos were no longer visible within the corrosion cavity. Seed production capacity can vary widely. Cones may have between 138.55 and 171.55 ovuliferous scales, seed potentials of 161.4 to 193.0 and seed efficiencies of 31.6 to 84.4 percent. However, in seeds that contain viable embryos germination potential was consistently high. All five clones had germination percentages of 96.0% or better and very similar germination profiles, with the maximum (non­-cumulative) number of germinated seeds occurring 11 days after stratification.99 pagesAvailable to the World Wide WebUN SDG 14: Life Below WaterThesis