the seedless vascular pants: ferns and their relatives

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The Seedless Vascular Pants: Ferns and Their Relatives

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Page 1: The Seedless Vascular Pants: Ferns and Their Relatives

The Seedless Vascular Pants: Ferns and Their Relatives

Page 2: The Seedless Vascular Pants: Ferns and Their Relatives

Outline

• Phylum Psilotophyta (Whisk Ferns) • Phylum Lycophyta (Club Mosses)• Phylum Equisetophyta (Horsetails)• Phylum Polypodiophyta (Ferns)• Fossils

Page 3: The Seedless Vascular Pants: Ferns and Their Relatives

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")

Page 4: The Seedless Vascular Pants: Ferns and Their Relatives

Classification of Seedless Vascular Plants1. 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)

Page 5: The Seedless Vascular Pants: Ferns and Their Relatives

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.

Page 6: The Seedless Vascular Pants: Ferns and Their Relatives

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-Alikes1. Fossils resembling Psilotum present in Silurian formations.

2. Rhynia and Zosterophyllum

- likely ancestors of club mosses (lycopods)

Page 7: The Seedless Vascular Pants: Ferns and Their Relatives

Fig. 21.1

Page 8: The Seedless Vascular Pants: Ferns and Their Relatives
Page 9: The Seedless Vascular Pants: Ferns and Their Relatives

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.

Page 10: The Seedless Vascular Pants: Ferns and Their Relatives

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.

Page 11: The Seedless Vascular Pants: Ferns and Their Relatives

Fig. 21.3

Page 12: The Seedless Vascular Pants: Ferns and Their Relatives

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.

Page 13: The Seedless Vascular Pants: Ferns and Their Relatives
Page 14: The Seedless Vascular Pants: Ferns and Their Relatives

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).

Page 15: The Seedless Vascular Pants: Ferns and Their Relatives

Fig. 21.5

Page 16: The Seedless Vascular Pants: Ferns and Their Relatives

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.

Page 17: The Seedless Vascular Pants: Ferns and Their Relatives
Page 18: The Seedless Vascular Pants: Ferns and Their Relatives

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.

Page 19: The Seedless Vascular Pants: Ferns and Their Relatives
Page 20: The Seedless Vascular Pants: Ferns and Their Relatives

Fig. 21.7

Page 21: The Seedless Vascular Pants: Ferns and Their Relatives

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.

Page 22: The Seedless Vascular Pants: Ferns and Their Relatives

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.

Page 23: The Seedless Vascular Pants: Ferns and Their Relatives

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

Page 24: The Seedless Vascular Pants: Ferns and Their Relatives

Fig. 21.10

Page 25: The Seedless Vascular Pants: Ferns and Their Relatives
Page 26: The Seedless Vascular Pants: Ferns and Their Relatives

Phylum Equisetophyta

• Human and Ecological Relevance Many giant horsetails used for food. Scouring rush stems used for scouring and

sharpening.

Page 27: The Seedless Vascular Pants: Ferns and Their Relatives

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.

Page 28: The Seedless Vascular Pants: Ferns and Their Relatives

Fig. 21.16

Page 29: The Seedless Vascular Pants: Ferns and Their Relatives
Page 30: The Seedless Vascular Pants: Ferns and Their Relatives

Spore Release From a Fern Sporangium

Page 31: The Seedless Vascular Pants: Ferns and Their Relatives

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.

Page 32: The Seedless Vascular Pants: Ferns and Their Relatives

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.

Page 33: The Seedless Vascular Pants: Ferns and Their Relatives

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.

Page 34: The Seedless Vascular Pants: Ferns and Their Relatives

Fossils

• Petrifications Petrifications are uncompressed rock-like

material in which the original cell structure has been preserved.

Page 35: The Seedless Vascular Pants: Ferns and Their Relatives

Review

• Phylum Psilotophyta (Whisk Ferns) • Phylum Lycophyta (Club Mosses)• Phylum Equisetophyta (Horsetails)• Phylum Polypodiophyta (Ferns)• Fossils

Page 36: The Seedless Vascular Pants: Ferns and Their Relatives

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