Ferns
by Melissa Mulvany


Ostrich_Fern.jpg


Habitats - Most of the species are in the tropics, many species of ferns grow in temperate forests (which are what most forests we see are, with moderate rainfall, and a moderate climate). (MM)

Ferns are mostly found in shady, moist, woodland conditions although some species of ferns have adapted to dry habitats. There are abundant amounts in tropical rain forests. (AR)
They prefer conditions where their flaggellated sperm can swim to their eggs. (AP)


A Fossil fern, this shows that ferns have been around for a long time and fern ancestors look similar to modern-day ferns.
A Fossil fern, this shows that ferns have been around for a long time and fern ancestors look similar to modern-day ferns.
(AR)



Diagnostic Characteristics of Ferns- Ferns are considered to be pteridophytes, which is a type of plant that evolved later than bryophytes (also known as mosses and liverworts). Ferns are seedless plants, meaning there is no seed stage in the life cycle of the plant. Ferns are also the first plants that developed a vascular system, which means that it has vascular tissue. Vascular tissues are a group of cells that are attached to each other into something like a tube, and that can transport materials through them. Ferns were also one of the first plants that developed true roots and leaves. (MM)
They are made up of xylem tissue that transports water and phloem tissue which transports nutrients and sugar around the plant. (AP)
About 97% of pteridophytes are ferns. There are about 12,000 different species of fern. Ferns are most dominate in the tropics but can be found at all locations of flowering plants. The dominate ferns are sporophytes. Some ferns, instead of having spores borne on all leaflets, the leaflet are divided between spore baring and sterile, photosynthetic leaflets. (MS 13)


Basic Anatomy - Horizontal rhizomes, a plant that has a horizontal stem(RJ), which then have a lot of vascular systems connected to it. Vascular systems are in plants that have connected tissues for moving water and minerals through them. The leaves on ferns (aka fronds) are divided into many smaller leaves. The tip of the fern, also called the fiddlehead, is coiled and the leaves grow as the tip uncoils. Ferns have a vascular system, which means they can absorb water and nutrients through their roots and these nutrients can then travel up the stem via the vascular tissue. Ferns are seedless plants, and they also have relatively large leaves. (MM)
Ferns have large leaves known as megaphylls attached to their branched vascular system. (AP)

FERNWIKI.jpg
Some anatomical features of the fern. (PS http://kentsimmons.uwinnipeg.ca/16cm05/16labman05/lb3pg5.htm)


Regarding the stems, most often there is a underground creeping rhizome, but sometimes there is an above-ground creeping stolon (e.g., Polypodiaceae), or an above-ground erect semi-woody trunk (e.g., Cyatheaceae) reaching up to 20 m in a few species (e.g., Cyathea brownii and Cyathea medullaris ).(RW)

The rhizome is a “specialized, rootlike stem,” and “fronds are generally connected to the rhizome by a stalk, known technically as the stripe.” (MR; Source 16)
The fiddlehead leaf bud is also referred to as a crozier. In fiddleheads or croziers, the apex of the frond is located in the middle of the coil. This coil arrangement of leaves in a fern fiddlehead or crozier is technically referred to as circinate vernation. (MR; Source 16)

Reproduction- Ferns reproduce using clusters of sporangioa (aka spores or sori) that are underneath their leaves. Spores are reproductive structures that are adapted for surviving in unfavorable conditions as well as dispersal. (MB) To protect the clusters of sporangia (sporus), the fern produces a protective layer called the Indusium.(SP)These spores can be on the leaves in any sort of pattern, like lines or dots, and these patterns help to identify what kind of fern it is. They are often times arranged in groups of four. Spores contain oil droplets and sometimes chlorophyll in addition to their nucleus. Ferns drop millions of spores during their lifetime but very few land in an environment suitable for growth. (SP) The wind then comes and blows the spores away from the fern plant, and once the spores are in the air they can be carried far away to another area where they land, and hopefully produce another fern plant. (MM)
A video of swimming fern gametes (LPE)


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The Life Cycle of a Fern (VN)


The life cycle of ferns is characterized as having an alternation of a gametophyte phase and a sporophyte phase. A typical fern sporophyte is the large, familiar plant seen in nature. Its cells have the unreduced number of chromosomes, usually two sets. Most fern gametophytes are not seen in nature. A typical gametophyte is about 0.4 inches (1 cm) in diameter, multicellular, flat, heart-shaped, and green. Its cells have the reduced number of chromosomes, usually one set. (RW)

Major Types - The ferns that evolved hundreds of millions of years ago are in the pteridophyte member of the land plants, however there are over 12,000 different species of fern plants. The modern day pteriodphytes are the horsetails, whisk ferns, and regular ferns. (MM)

Many species of fern look very similar so it can be difficult to identify different types. In many cases differences among types of ferns can only be discernible upon close inspection of the stem and leaves and even so the differences may only be in the orientation of the leaves relative to one another. (JS)


There are six main divisions of ferns. Two are extinct. Although it can be difficult to tell ferns apart, the psilotales, or "whisk ferns", are relatively unique. Considered the least complex pteridophytes, psilotales have vascular tissue but lack roots and leaves. Their inclusion in the category of ferns is a bit shaky, since there are no fossils of them to indicate age. (Matt B - Source 6)

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Different types of ferns (ZJ)


Environmental Adaptations - Long ago, ferns grew near trees and in swampy forests during the Carboniferous period, but now ferns are very widespread (meaning far apart) and diverse (meaning there's a lot of different types). These plants adapted larger leaves than normal plants because of its branched vascular system. This adaptation formed because the many branches were able to supply a larger leaf with more water and minerals, which means that more sugar can be made during photosynthesis with the larger leaves. (MM)

Transport of Materials - Since ferns have a vascular system, all of the nutrients and water travel through the vascular system. Water and nutrients get absorbed by the roots of the plant, and then travel up the stem and through all the branches of the leaves. The nutrients get transported throughout the entire plant because each cell is joined together in a tube like structure and the nutrients pass through these tubes. (MM)


external image 250px-Fernanatomy.jpg



above shows the anatomy of a fern (CP source 4)

Fossil record for ferns start around 360 million years ago in the Carboniferous but many types of ferns did not appear until around 145 million years ago in the Crustaceous period. (CM)


Review Questions
What was the major adaptation of ferns that allowed them to move away from the water? (TB)
What are the major types of ferns? (AP)
What are the major stages of the fern life cycle? (JP)
What is the basic anatomy of the fern and how is it related to their capacities as organisms? (IL)

Citations:
- Campbell, Neil A., and Jane B. Reece. "Chapter 29: Plant Diversity I: How Plants Colonized Land." Biology. 6th ed. San Francisco: Pearson Education, Inc., 2002. Print.
- (May 29, 2005). Ostrich Fern Retrieved from: http://www.plantcare.com/oldSite/httpdocs/images/namedImages/Ostrich_Fern.jpg

http://www.aboutferns.com/types_of_ferns.shtml (JS)
4.
"Fern." Encyclopedia of Earth. Web. 06 Nov. 2011. <http://www.eoearth.org/article/Fern?topic=49480>. (CP)

http://ic.galegroup.com/ic/scic/ReferenceDetailsPage/ReferenceDetailsWindow?displayGroupName=Reference&disableHighlighting=false&prodId=SCIC&action=e&windowstate=normal&catId=&documentId=GALE%7CCV2644030885&mode=view (RW)

6. http://www.ucmp.berkeley.edu/plants/pterophyta/psilotales.html (Matt B)

7.http://www.alientravelguide.com/science/biology/life/plants/tracheo/pteropsi/fernlike.htm (AR)

8. http://www.sciencephoto.com/media/171366/enlarge (fossil picture) (AR)

9. Photograph. Life Cycle of A Fern. Cambell's Biology, 26 June 2004. Web. 11 Nov. 2011. <http://www.davidlnelson.md/Cazadero/Fern_Life_cycle.htm>. (VN)

10. __http://oak.ucc.nau.edu/rscott/BIO%20100%20files/ferns-angios.pdf__ (AP)
11. McDaniel, Stephen. "Introduction." American Fern Society. Web. 11 Nov. 2011. <http://amerfernsoc.org/>. (SP)

12. http://www.twferngarden.com/types-of-ferns-available-for-home-gardens (ZJ)

13.
"The Ferns." The University of the West Indies (UWI) at Ca9ve Hill, Barbados. Web. 14 Nov. 2011. <http://www.cavehill.uwi.edu/FPAS/bcs/bl14apl/pter2.htm>. (MS)
14.http://www.environment.gov.au/biodiversity/abrs/publications/other/species-numbers/index.html (RW)
15. http://www.youtube.com/watch?v=rBDhGIOhZLc (LPE)
16. "Ferns." The Gale Encyclopedia of Science. Ed. K. Lee Lerner and Brenda Wilmoth Lerner. 4th ed. Detroit: Gale, 2008. Gale Science In Context. Web. 3 Dec. 2011.