Introduction to the Plant Kingdom: Bryophytes

Chapter 20

Outline

Introduction

Phylum Hepaticophyta - Liverworts

Leafy Liverworts

Phylum Anthocerophyta - Hornworts

Phylum Bryophyta - Mosses

 

 

 

Introduction

About 23,000 species of bryophytes.

Include mosses, liverworts, and hornworts.

Habitats range in elevation from sea level up to 5,500 m or more.

Bryophytes of all phyla often have mycorrhizal fungi associated with their rhizoids.

In some instances, fungi apparently are at least partially parasitic.

Introduction

Peat mosses are ecologically important in bogs.

Luminous mosses are found in caves and in other dark, damp places.

None have true xylem or phloem.

Many have hydroids.

Exhibit alteration of generations.

Phylum Hepaticophyta

Liverworts

Structure and Form

Most common liverworts have flattened, lobed thalli.

Gametophyte stage develops from spores.

When spores germinate they may produce immature gametophyte (protonema).

Phylum Hepaticophyta

Thalloid Liverworts

Best known species are in the genus Marchantia.

Thick thallus that forks dichotomously as it grows.

Consists of parenchyma cells with few, if any, chloroplasts.

Section of Marchantia Thallus

Asexual Reproduction of Marchantia

Leafy Liverworts

Always have two rows of partially overlapping "leaves" whose cells contain distinctive oil bodies.

Often have folds and lobes.

Archegonia and antheridia are produced in cup-like structure.

At maturity, sporophyte capsule may be pushed out as the seta elongates.

Germinating spore produces a protonema.

Marchantia Sporophyte

Phylum Anthocerophyta

Hornworts

Structure and Form

Mature sporophytes look like miniature greenish-blackish rods.

Only about 100 species worldwide.

Thalli have pores and cavities filled with mucilage, that often contain nitrogen-fixing bacteria.

Hornwort Sporophyte

Hornworts

Asexual Reproduction

Fragmentation

Separation of lobes from thallus.

Sexual Reproduction

Archegonia and antheridia are produced in rows beneath the upper surface of the gametophytes.

Have both unisexual and bisexual plants.

Phylum Bryophyta

Mosses

Structure, Form, and Classes

About 15,000 species of mosses currently known.

Divided into three classes:

Peat Mosses

True Mosses

Rock Mosses

Mosses

"Leaves" of moss gametophytes have no mesophyll tissue, stomata, or veins.

Blades are nearly always one-cell thick, and are never lobed or divided.

Initially formed in three ranks and usually end up appearing to be arranged in a spiral or alternately on an axis that twists as it grows.

Sexual Reproduction:

 

 

. Bryophyte Reproductive Cycle

. The Gametophyte is the Complex Photosynthetic Organism for mosses (Bryophyta).

. The Gametangia are formed at the apex of the stems which are called "Leafy Gametophores".

. Male Plants tend to have an open, cup-shaped apex with reflexed Leaves. This forms a bowl-like structure.

. Elongated Antheridia are produced in the Bowl.

. Stems that produce Archegonia have pointed apices because the leaves enclose the Archegonia.

. The ZYGOTE marks the start of the Diploid (Sporophyte) Generation!

. The Shoot Apex of the Embryo grows directly out of the Archegonial Neck (Exoscopic). However, the Archegonial Neck grows to enclose the developing Sporophyte. This forms the Calyptra.

. The Sporophyte eventually causes the calyptra to rupture but some of it is carried aloft by the elongating Sporophyte.

. The Sporophyte has 3 parts.

. The Sporangium (Capsule) develops at the apex of the Sporophyte.

. Meiosis marks the start of the
Haploid Gametophyte Generation

.

Phylum Bryophyta

Human and Ecological Relevance

Pioneer Species of Primary Succession

Indicators of Surface Water

Packing Material

Peat Mosses

Soil Conditioner

Poultice Material

Fuel

Review

Introduction

Phylum Hepaticophyta - Liverworts

Leafy Liverworts

Phylum Anthocerophyta - Hornworts

Phylum Bryophyta - Mosses

 

 

 

 

 

 

 

 

.

The Seedless Vascular Pants:
Ferns and Their Relatives

Chapter 21

Outline

Phylum Psilotophyta (Whisk Ferns)

Phylum Lycophyta (Club Mosses)

Phylum Equisetophyta (Horsetails)

Phylum Polypodiophyta (Ferns)

Fossils

 

 

 

 

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:

 

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.

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.

Reproduction

 

Phylum Lycophyta

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).

Reproduction

 

Phylum Lycophyta

Isoetes - Quillworts

Most found in areas partially submerged in water, and least part of the year.

Microphylls are arranged in a tight spiral on a stubby stem.

Ligules occur towards leaf base.

Corms have vascular cambium.

Reproduction

 

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.

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 hollow central canal.

Aerial stems develop from horizontal rhizomes.

Reproduction

 

Phylum Equisetophyta

Human and Ecological Relevance

Many giant horsetails used for food.

Scouring rush stems used for scouring and sharpening.

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.

 

Spore Release From a Fern Sporangium

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.

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.

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.

Fossils

Petrifications

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

Review

Phylum Psilotophyta (Whisk Ferns)

Phylum Lycophyta (Club Mosses)

Phylum Equisetophyta (Horsetails)

Phylum Polypodiophyta (Ferns)

Fossils

The Seedless Vascular Pants:
Ferns and Their Relatives

Chapter 21

Outline

Phylum Psilotophyta (Whisk Ferns)

Phylum Lycophyta (Club Mosses)

Phylum Equisetophyta (Horsetails)

Phylum Polypodiophyta (Ferns)

Fossils

 

 

 

 

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:

 

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.

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.

Reproduction

 

Phylum Lycophyta

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).

Reproduction

 

Phylum Lycophyta

Isoetes - Quillworts

Most found in areas partially submerged in water, and least part of the year.

Microphylls are arranged in a tight spiral on a stubby stem.

Ligules occur towards leaf base.

Corms have vascular cambium.

Reproduction

 

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.

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 hollow central canal.

Aerial stems develop from horizontal rhizomes.

Reproduction

 

Phylum Equisetophyta

Human and Ecological Relevance

Many giant horsetails used for food.

Scouring rush stems used for scouring and sharpening.

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.

 

Spore Release From a Fern Sporangium

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.

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.

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.

Fossils

Petrifications

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

Review

Phylum Psilotophyta (Whisk Ferns)

Phylum Lycophyta (Club Mosses)

Phylum Equisetophyta (Horsetails)

Phylum Polypodiophyta (Ferns)

Fossils

 

 

 

.    Pterophyta (Ferns)    

The Pterophyta is a familiar plant taxon, especially in Hawaii. They have a prominent position in our terrestrial ecosystems both as ground cover species and canopy components in certain environments.

. compared to woody Angiosperms (flowering plants) and Gymnosperms.

. Ferns typically have subterranean stems called Rhizomes. Some species have Stolons. Most species are Terrestrial but some are Epiphytic and a few are Aquatic.

. Roots are adventitous and arise from the stem. The stems of tree ferns have a thick coat formed by adventitous roots which are initiated near the apex of the stem and grow down the outside of the stem. This has some obvious disadvantages. The roots must travel a long distance through the atmosphere before reaching the soil..

. Consequently, water loss can readily occur over this distance. They are also subjected to any biotic or abiotic events that occur over this expanse

. A Leaf Gap occurs when part of the vascular tissue in the stem is diverted towards the leaf. This is called a Leaf Trace. The integrity of the stele is restored above the Leaf Gap. When separate vascular bundles constitute the Stele, they may fork to produce Stem Traces which unite above the Leaf Gap to reform the Vascular Bundle. Parenchyma cells replace the Leaf Trace above the

. level of its divergence. Consequently, if you make a series of cross sections of a stem, it will appear that a gap occurs in the Stele near the level where the Leaf Trace diverged. The Diagrams below attempt to depict ways in which this could occur

. This fern (Dicksonia) has a  Siphonostele which has a hollow cylinder of Vascular Tissue. Part of the Stele diverges into the leaf bases which are clustered around the circumference of the stem. The Leaf Traces are V-shaped and the

. entire profile of the Stele and the Leaf Traces resembles a sun and rays emanating from it. The Leaf Gaps are the light areas that intervene and "break up" the circular outline of the Stele.

. The predominate organizational pattern for fern leaves is Pinnate. This means that a structure has one central axis which produces lateral structures that are opposite each other along the central axis. A bird feather is a good example of a structure that has pinnate organization.

.

. A Fern leaf is often called a Frond.

. The presence of Megaphylls and their associated Leaf Gaps in the Stele result in the occurrence of complex stelar organization in some ferns. Leafy stems have dissected steles while Rhizomes (produce few or no leaves) have relatively undissected steles.

. Fern Stele that contains separate vascular bundles. This is a Dictyostele
(Divided Stele)

. Close inspection of the leaf below shows that it has Dichotomous Venation.

. Dichotomous Venation is characterized by the repeated bifurcation (split in two) at the tip of each vein. This is repeated over and over. Reticulate Venation is characterized by a more intricate pattern of branches which become progressively smaller and smaller until the surround a small area called an Areole. The ultimate branch vein terminates within the Areole.

. This is a Derived "Advanced" trait which is associated with flowering plants.

. Fern Leaves have a unique manner of development. The immature leaves are tightly coiled into a structure called a "fiddlehead". During maturation, the leaf uncoils from the bottom to its top (acropetal).

. Leaf Anatomy can be simple or can be as complex as that seen with flowering plants. The take home message is that fern leaves are highly sophisticated in their design and represent a major advance over the Microphyll!

. Fern Apical Meristems tend to have Apical Cells. The small structures along the flank of the stem apex are Scales. These protect the immature leaves and the Shoot Apical Meristem.