CHAPTER 21: Ferns

In this chapter you will learn about a brief review of the features that distinguish the major groups of vascular plants without seeds from one another and from the bryophytes and then discusses representatives of each Phylum. Included in the discussion are whisk ferns (Psilotum), club mosses (Lycopodium, Selaginella), horsetails (Equisetum), and ferns. A digest of the human and ecological relevance of each group is given, and life cycles of representatives are illustrated.

At the end of this chapter the successful student will be able to

Recognize the 4 most common phyla of ferns:
Assignments
Glossary

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Recognize the characteristic of Phylum Psilotophyta

The Whisk Ferns
- Loosely resemble small, green whisk brooms.
- Structure and Form
  - Sporophytes consist almost entirely of dichotomously forking aerial stems.
    - Have neither leaves nor roots.
      - Enations spirally arranged along stems.
Life Cycle:

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Recognize the characteristic of Phylum Lycophyta

Ground Pines, Spike Mosses, and Quillworts
- Collectively called club mosses.
  - Only two living representatives of two major genera.
    - Lycopodium
    - Selaginella
- Sporophytes have microphylls.
- Have true roots and stems.
Lycopodium - Ground Pines
- Often grow on forest floors.
- Resemble little Christmas trees, complete with cones.
- Stems are simple or branched.
  - Develop from branching rhizomes.
- Life Cycle:
Selaginella - Spike Mosses
- Especially abundant in tropics.
- Branch more freely than ground pines.
- Leaves have a ligule on upper surface.
- Produce two different kinds of spores and gametophytes (heterospory).
- Life Cycle:

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Recognize the characteristics of Phylum Equisetophyta

Recognize the characteristics of the species Horsetails and Scouring Rushes
- Structure and Form
  - About 25 species scattered through all continents.
  - Significant silica deposits accumulate on the inner walls of the stem’s epidermal cells.
  - Branches, when present, are normally in whorls at regular intervals along the jointed stems.
- Both branched and unbranched species have tiny microphylls in whorls at the nodes.
- Leaves fused at their base forming a collar.
- Stems are distinctly ribbed and have obvious nodes and internodes.
  - Pith breaks down at maturity leaving a hollow central canal.
  - Aerial stems develop from horizontal rhizomes.
- Lifecycle:
Human and Ecological Relevance
- Many giant horsetails used for food.
- Scouring rush stems used for scouring and sharpening

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Recognize the characteristics of Phylum Polypodiophyta

The Ferns
- Structure and Forms
  - Approximately 11,000 known species of ferns vary in size from tiny floating forms less than 1 cm to giant tropical tree ferns up to 25 m tall.
    - Fern leaves are megaphylls that are commonly referred to as fronds.
      - Typically divided into smaller segments.
Lifecycle of Ferns Click here to see an interactive of the lifecycle
Spore Release From a Fern Sporangium
Human and Ecological Relevance
- Extremely popular house plants.
  - Serve as air filters.
- Cooked rhizomes serve as food.
- Folk Medicine
- Fronds used in thatching houses.

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