I am a PhD student working with Paul Wolf at Utah State University.
My dissertation research is on the pan-tropical fern genus Ceratopteris, also known as the water sprite ferns. This aquatic, short-lived plant has been used as a model organism since the 1980s, with the species C. richardii (also called the C-fern) most commonly found in lab. While a great deal is known about the developmental biology of this fern, less is understood about the evolutionary relationships between the species in the genus. My research will examine the different species of water sprite ferns and result in the first monographic revision of the genus based on molecular markers.
Ferns have unique life cycle that stands out from the other lineages of land plants (the bryophytes and seed plants). All of these plants go through what is known as the Alternation of Generations, where they switch between the gametophyte and sporophyte generations. The sporphyte is the spore-bearing life stage; the gametophyte is the gamete-bearing life stage. In bryophytes, the sporphyte generation is completely dependent on the gametophyte generation; in the seed plants, the gametophyte is completly dependent on the sporophyte generation. Ferns are unusual in that the gametophyte and sporophyte life stages are entirely separate. In the image below, the parts of the life cycle in blue represent the gametophyte (haploid)), and the sporophyte parts are shown in pink (diploid). This unique life history of ferns makes them not only interesting organisms to study, but they can serve as an evolutionary midpoint between the other two major lineages of land plants, a critical group for comparative studies.
Biology of Plants, Raven et al. 2005
~ The Sporophyte Generation ~
Fern sporophytes are the leafy plants that you most commonly see. There are a variety of shapes, sizes, and life histories of fern sporophytes, but one thing they all have in common is that they produce spores on the underside of their leaves. These spores are created and dispersed from within a sporangium. A collection of sporangia (the small dots you see on the underside of a fern leaf) is called a sorus (plural sori).
In some species of ferns, the sporangia have a unique way of dispersing their spores. They will slowly crack open and curl back as they dry, then all at once snap closed again, flinging the spores within away from the mother plant. Below is a video made by fern researcher Fernando Matos of spore-shooting in real time.
~ The Gametophyte Generation ~
Once the spores have been dispersed to a suitable habitat, they will germinate and start to grow into gametophytes. There are two main types of fern gametophytes: heart and strap shaped. The former are mostly characteristic of terrestrail, water-loving ferns; the latter are more common in epiphytic or drought-tolerant ferns.
Heart-shaped gametophytes, image source
All gametophytes have the ability to produce both sperm and eggs. The former is produce from a specialized organ called the antheridia, the later from the archegonia. Most ferns require water to move the sperm from the antheridia to the egg waiting within the archegonia - this is why you see many more ferns in areas like rainforests, as opposed to dry deserts. However, there are many fern species adapted to very dry habitats, and they have some interested adaptations to get around the need for water in fertilization.