Fern Reproduction and Life Cycle

Study Notes

Ferns are a group of seedless, vascular plants with approximately 20,000 species, occupying a wide range of habitats from temperate to tropical.
They prefer shady, moist environments and have roots, stems, and leaves called fronds.
Ferns reproduce through spores, undergoing two generations of plants to complete the life cycle, known as alternative generation.

Alternative generation refers to lifecycles that alternate between haploid and diploid individuals, common in algae and terrestrial plants.
Haploid cells contain one set of chromosomes (n), while diploid cells have two sets of chromosomes (2n).

Spores are found on the underside of the blade or pinnae, containing genetic material needed to grow a new plant.
Spores are coated in sporangia, often brown, yellow, or red in color.
When spores are released in optimal growing conditions, they form a haploid, multicellular gametophyte through mitosis.
The gametophyte contains either antheridia (male structure) or archegonia (female structure).

With the presence of water, antheridia use flagella to swim to archegonia and fertilize, creating a diploid sporophyte.
The sporophyte contains two sets of chromosomes (2n) and can produce haploid spores through meiosis.
The sporophyte develops into an adult spore-producing fern.

Apogamy occurs when a sporophyte grows from a gametophyte without fertilization, often in dry environments.
Ferns can also reproduce from bulbets, small vegetative buds that grow from proliferous frond tips.
Bulbets will either fall off the frond or be pressed into the ground, developing rhizomes that grow into the soil.

The life cycle of a fern has two distinct life stages: diploid and haploid.
The fern undergoes two generations to complete the life cycle, known as alternative generation.
The haploid stage begins with a spore undergoing mitosis to create a gametophyte.
The gametophyte develops male and female structures that produce gametes, which fertilize to form a zygote.
The diploid stage begins with the development of a sporophyte from the zygote, which grows into a mature fern producing new spores.