Relatives of primitive gymnosperms first appear in the fossil record early in the Carboniferous Period, about 350 MYBP. As world climates became more arid, the gymnosperms increased in importance and became dominant around 200 MYBP. Meanwhile, flowering plants appeared in the fossil record close to 135 MYBP and afterwards expanded to their current dominance.

Part of the reason these groups replaced the lower vascular plants concerned modifications in their reproductive systems. Lower vascular plants and bryophytes demonstrate certain adaptations to a terrestrial existence; however, some aspects are hardly different from the ancestral style of the algae, such as the direct release of gametes into the environment. In this lab you’ll investigate how transfer of gametes in conifers and flowering plants differs from the more primitive groups.