1. The Seedless Vascular Pants: Ferns and Their Relatives

2. Outline
Phylum Psilotophyta (Whisk Ferns)
Phylum Lycophyta (Club Mosses)
Phylum Equisetophyta (Horsetails)
Phylum Polypodiophyta (Ferns)
Fossils

3. Features of Seedless Vascular Plants 1
Features of Seedless Vascular Plants 1. Xylem and phloem present • internal conducting tissues for water and food, respectively 2. Spores, but no seeds 3. Ferns and relatives ("fern allies")

4. Classification of Seedless Vascular Plants
1. Phylum Psilotophyta (Whisk Ferns)
• no true leaves or true roots
2. Phylum Lycophyta (Club Mosses and Quillworts)
• small leaves with a single vein called microphylls (most photosynthetic)
3. Phylum Equisetophyta (Horsetails & Scouring Rushes)
• ribbed stems containing silica deposits and whorled leaves
4. Phylum Polypodiophyta (Ferns)
• large, complex leaves called megaphylls (more than one vein)

5. 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 superficially leaflike, photosynthetic flaps of tissue, spirally arranged along stems.

6. Life Cycle of the Whisk Fern Psilotum
1. Small sporangia borne on short stubby branches
2. Meiosis occurs in sporangia producing meiospores
3. Meiospores germinate slowly on soil or bark of tree ferns
4. Gametophytes found beneath the soil, very small (2 mm X 6 mm)
5. Archegonia and antheridia produced on this colorless gametophyte
6. Fertilization occurs in the archegonium
7. Sporophyte develops from the zygote
Fossil Whisk Fern Look-Alikes
1. Fossils resembling Psilotum present in Silurian formations.
2. Rhynia and Zosterophyllum
- likely ancestors of club mosses (lycopods)

7. Fig. 21.1

9. Phylum Lycophyta
Ground Pines, Spike Mosses, and Quillworts
Collectively called club mosses.
Only two living representatives of two major genera.
Lycopodium (50 species)
Selaginella (700 species)
Sporophytes have small leaves called microphylls.
Have true roots and stems.

10. Phylum Lycophyta
Lycopodium - Ground Pines
Often grow on forest floors.
Resemble little Christmas trees, complete with cones.
Stems are simple or branched.
Develop from branching rhizomes.

11. Fig. 21.3

12. Reproduction in the ground pine Lycopodium
1. Strobilus (conelike stucture)formed in many species.
2. Sporophylls with sporangia. Meiosis occurs in sporangia.
3. Meiospores germinate in the soil and produce gametophytes with archegonia and antheridia.
4. Fertilization occurs in archegonium, producing zygote.
5. Zygote develops into mature sporophyte.
6. Asexual propagation may occur by bulbils, small small budlike structures produced in the axils of leaves.

14. Phylum Lycophyta
Selaginella - Spike Mosses
Especially abundant in tropics.
Branch more freely than ground pines.
Leaves have a ligule (an extra appendage) on upper surface.
Produce two different kinds of spores and gametophytes (heterospory).

15. Fig. 21.5

16. Reproduction in the spike moss Selaginella
1. Sporangia produced on microsporophylls and megasporophylls.
2. Microsporangia and megasporangia produce microspores and megaspores.
3. Microspores develop into male gametopyte.
4. Megaspores develop into female gametophytes.
5. Gametophytes develop within the confines of the microspore and megaspore walls.
6. Fertilization and development of sporophytes similar to ground pines.

18. Phylum Lycophyta
Isoetes - Quillworts
Most found in areas partially submerged in water, and least part of the year.
Long microphylls (grass-like in appearance).
Microphylls are arranged in a tight spiral on a stubby stem.
Ligules occur towards leaf base.
Corms have vascular cambium.
Reproduction
Similar to spike mosses.

20. Fig. 21.7

21. Human & Ecological Relevance of Club Mosses and Quillworts
1. Little economic importance.
2. Lycopodium: spores used as flash powder and other uses.
3. Selanginella: resurrection plants, sold as novelties.
4. Lycopodium: woven into wreaths and holiday decorations.
5. Isoetes: quillwort corms can be eaten by animals, birds, and humans.

22. Phylum Equisetophyta
The 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.

23. Phylum Equisetophyta
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 central canal
Vascular tissues with carinal canals (water). Cortex with vallecular canals (air)
Aerial stems develop from rhizomes
Reproduction

24. Fig

26. Phylum Equisetophyta
Human and Ecological Relevance
Many giant horsetails used for food.
Scouring rush stems used for scouring and sharpening.

27. 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.

28. Fig

30. Spore Release From a Fern Sporangium

31. Phylum Polypodiophyta
Human and Ecological Relevance
Extremely popular house plants.
Serve as air filters.
Cooked rhizomes serve as food.
Folk Medicine
Fronds used in thatching houses, weaving baskets.

32. Fossils
A fossil is generally defined as any recognizable prehistoric organic object preserved from past geological ages.
Conditions of formation almost always include quick burial in an accumulation of sediments.
Hard parts more likely preserved than soft parts.

33. Fossils
Molds, Casts, Compressions, and Imprints
After being buried in sediment, the organic material may be slowly washed away by water percolating through the rock pores.
If air space remains - Mold
If silica fills space - Cast
Compression takes place when objects are buried by layers of sediment and greatly compressed so that only a thin outline is left.

34. Fossils
Petrifications
Petrifications are uncompressed rock-like material in which the original cell structure has been preserved.

35. Review
Phylum Psilotophyta (Whisk Ferns)
Phylum Lycophyta (Club Mosses)
Phylum Equisetophyta (Horsetails)
Phylum Polypodiophyta (Ferns)
Fossils

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