16 Questions
What characteristic distinguishes ferns from lycophytes?
Presence of true roots and stems
What is the dominant generation in ferns?
Diploid sporophyte
What is the term for plants that grow on rocks?
Epipetric
When did the oldest ferns appear?
360 million years ago, during the Carboniferous period
What is the term for the small brown or black dots on the undersides of fern megaphylls?
Sori
What is the term for the haploid stage of the fern life cycle?
Gametophyte
What is the characteristic of the smaller herbaceous ferns?
They can grow as epiphytes
When did most modern fern groups appear?
145 million years ago, during the Cretaceous period
What happens to the fern gametophyte after an egg cell has been fertilized?
It germinates into a new diploid sporophyte
What is the function of the archegonial heads in fern gametophytes?
To produce egg cells through mitosis
Why is it important to properly identify fern species?
Because some species are poisonous
What characteristic feature is used to identify the fern sporophyte generation?
The presence of fiddleheads
What is the reproductive strategy of many fern sporophytes?
Vegetative reproduction through rhizomes
What is the outcome when an egg cell is fertilized by a sperm cell in fern gametophytes?
The formation of a new sporophyte generation
What is the consequence of some fern species becoming aggressive weeds in disturbed areas?
They outcompete native species
What is the advantage of fern sporophytes over gametophytes?
They are able to grow in the same spot year after year
Study Notes
Evolution of Vascular Plants
- Ferns are more advanced vascular plants than lycophytes, with true roots and stems.
- Ferns have leaf-like structures called megaphylls, which are larger versions of microphylls.
Characteristics of Ferns
- Most fern species are herbaceous plants, meaning no woody stems above the ground.
- Some ferns can grow up to 25 meters tall, while others can grow as epiphytes or epipetric.
- Ferns appeared during the Carboniferous period (360 million years ago) and modern fern groups during the Cretaceous period (145 million years ago).
Reproduction in Ferns
- The diploid sporophyte is the dominant generation in ferns.
- Sori, or groups of sporangia, are found on the back or undersides of megaphylls, producing haploid spores through meiosis.
- Spores germinate into new haploid gametophytes, which attach to the soil with rhizoids and bear reproductive heads.
- Gametophytes can self-fertilize, producing a new diploid sporophyte directly.
Fern Gametophytes
- Gametophytes are small, ephemeral, and not well-known in the wild.
- Most knowledge about fern gametophytes comes from laboratory studies.
- Antheridial heads produce sperm cells, while archegonial heads produce egg cells, both through mitosis.
- Sperm cells can swim to the archegonial heads, fertilizing the egg cells.
Fern Sporophytes
- Fern sporophytes are readily identified by the characteristic "fiddlehead" curved stem.
- Many fern sporophytes are perennial, growing in the same spot year after year.
- Some fern sporophytes can engage in vegetative reproduction, propagating new plants via rhizomes.
- This reproductive strategy has caused some fern species to become aggressive weeds in disturbed areas.
This quiz covers the evolution of vascular plants, from the first lycophytes to the more advanced ferns, discussing their characteristics and features.
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