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 Photo shows a horsetail with a thick stem and whorls of thin stems branching from it.
Thin leaves originating at the joints are noticeable on the horsetail plant. (credit: Myriam Feldman)

Ferns

Ferns are considered the most advanced seedless vascular plants and display characteristics commonly observed in seed plants. Ferns form branching roots and large leaves known as fronds. With their large fronds, ferns are the most readily recognizable seedless vascular plants ( [link] ). About 12,000 species of ferns live in environments ranging from tropics to temperate forests. Although some species survive in dry environments, most ferns are restricted to moist and shaded places. They made their appearance in the fossil record during the Devonian period (416–359 million years ago) and expanded during the Carboniferous period, 359–299 million years ago ( [link] ).

The dominant stage of the lifecycle of a fern is the sporophyte, which consists of large compound leaves called fronds. Fronds fulfill a double role; they are photosynthetic organs that also carry reproductive organs. The stem may be buried underground as a rhizome, from which adventitious roots grow to absorb water and nutrients from the soil; or, they may grow above ground as a trunk in tree ferns ( [link] ). Adventitious organs are those that grow in unusual places, such as roots growing from the side of a stem.

 Photo shows a potted fern.
Some specimens of this short tree-fern species can grow very tall. (credit: Adrian Pingstone)
 This chart shows a geological time scale, starting with the Pre-Archean eon about 3800 million years ago, and ending with the Quaternary period in the Cenozoic era in the Phanerozoic eon about 1.6 million years ago. The Devonian period and Carboniferous period are both in the Paleozoic era. The Devonian period began 410 million years ago and ended 360 million years ago. The Carboniferous period was from 360 million years ago to 290 million years ago.
This chart shows the geological time scale, beginning with the Pre-Archean eon 3800 million years ago and ending with the Quaternary period in present time. (credit: modification of work by USGS)

The lifecycle of a fern is depicted in [link] . The sporophyte is the most conspicuous stage of the lifecycle. On the underside of its mature fronds, sori (singular, sorus) form as small clusters where sporangia develop ( [link] ).

Art connection

 The fern life cycle begins with a diploid (2n) sporophyte, which is the fern plant. Sporangia are round bumps that occur on the bottom of the leaves. Sporangia undergo mitosis to form haploid (1n) spores. The spores germinate and grow into a green gametophyte 1n that resembles lettuce. The gametophyte contains antheridia that produce, sperm and archegonia that produce eggs. Inside the archegonium the sperm fertilizes the egg, forming a diploid (2n) zygote. The zygote undergoes mitosis to form a 2n sporophyte, ending the cycle.
This life cycle of a fern shows alternation of generations with a dominant sporophyte stage. (credit "fern": modification of work by Cory Zanker; credit "gametophyte": modification of work by "Vlmastra"/Wikimedia Commons)

Which of the following statements about the fern life cycle is false?

  1. Sporangia produce haploid spores.
  2. The sporophyte grows from a gametophyte.
  3. The sporophyte is diploid and the gametophyte is haploid.
  4. Sporangia form on the underside of the gametophyte.

Concept in action

Go to this website to see an animation of the lifecycle of a fern and to test your knowledge.

 The photo shows small bumps called sori on the underside of a fern frond.
Sori appear as small bumps on the underside of a fern frond. (credit: Myriam Feldman)

Inside the sori, spores are produced by meiosis and released into the air. Those that land on a suitable substrate germinate and form a heart-shaped gametophyte, which is attached to the ground by thin filamentous rhizoids ( [link] ).

 The photo shows a young sporophyte with a fan-shaped leaf growing from a lettuce-like gametophyte.
Shown here are a young sporophyte (upper part of image) and a heart-shaped gametophyte (bottom part of image). (credit: modification of work by "Vlmastra"/Wikimedia Commons)

The inconspicuous gametophyte harbors both male and female gametes (the sperm and the egg). Flagellated sperm released from the antheridium swim on a wet surface to the archegonium, where the egg is fertilized. The newly formed zygote grows into a sporophyte that emerges from the gametophyte and grows by mitosis into the next generation sporophyte.

Questions & Answers

what is mutation
Janga Reply
what is a cell
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Sifune
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mahase Reply
classification of plants, gymnosperm features.
Linsy Reply
what is the features of gymnosperm
Linsy
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Samuel
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urine is formed in the nephron of the renal medulla in the kidney. It starts from filtration, then selective reabsorption and finally secretion
onuoha Reply
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Jeremiah
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Konadu
how is urine formed in human
Rahma
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Pelagie Reply
what is the causative agent of malaria
Diamond
malaria is caused by an insect called mosquito.
Naomi
Malaria is cause by female anopheles mosquito
Isaac
Malaria is caused by plasmodium Female anopheles mosquitoe is d carrier
Olalekan
a canal is more needed in a root but a cavity is a bad effect
Commander
what are pathogens
Don Reply
In biology, a pathogen (Greek: πάθος pathos "suffering", "passion" and -γενής -genēs "producer of") in the oldest and broadest sense, is anything that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ. The term pathogen came into use in the 1880s.[1][2
Zainab
A virus
Commander
Definition of respiration
Muhsin Reply
respiration is the process in which we breath in oxygen and breath out carbon dioxide
Achor
how are lungs work
Commander
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Achiri Reply
in the mouth
EZEKIEL
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stimulates the follicle to release the mature ovum into the oviduct
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Chinaza
endocrine secrete hormone and regulate body process
Achor
while pituitary gland is an example of endocrine system and it's found in the Brain
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Egbodo Reply
Biology is the study of living organisms, divided into many specialized field that cover their morphology, physiology,anatomy, behaviour,origin and distribution.
Lisah
biology is the study of life.
Alfreda
Biology is the study of how living organisms live and survive in a specific environment
Sifune
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Source:  OpenStax, Bi 101 for lbcc ilearn campus. OpenStax CNX. Nov 28, 2013 Download for free at http://legacy.cnx.org/content/col11593/1.1
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