The Seedless Vascular Plants: Ferns and Their Relatives - PowerPoint Presentation

Slide1

The Seedless Vascular Plants: Ferns and Their Relatives

Chapter 21Slide2

Outline

Introduction

Phylum

Psilotophyta

– The Whisk Ferns

Phylum

Lycophyta

– The Ground Pines, Spike Mosses and

Quillworts

Phylum

Equisetophyta

– The Horsetails and Scouring Rushes

Phylum

Polypodiophyta

– The

FernsSlide3

Introduction

During early stages of vascular plant evolution:

Internal conducting tissue

developed

True leaves

appeared

Roots

functioning

in absorption and anchorage

developed

Gametophytes became progressively

smaller

4

phyla of seedless vascular plants:

Psilotophyta

,

Lycophyta

,

Equisetophyta

,

PolypodiophytaSlide4

Introduction

Psilotophyta

Sporophytes

without true leaves or roots

Stems and rhizomes fork

evenly

LycophytaPlants covered with microphylls - leaves with single vein whose trace not associated with leaf gap

Psilotum

LycopodiumSlide5

Introduction

Equisetophyta

Sporophytes

with

ribbed stems containing

silica

W

horled, scalelike microphylls lacking chlorophyllPolypodiophytaSporophytes with megaphylls

- leaves with >1 vein

and leaf trace associated with leaf gapOften large and divided

Equisetum

A fernSlide6

Phylum

Psilotophyta

– The Whisk Ferns

Resemble small, green whisk brooms

Structure

and form:

Sporophytes

: Dichotomously forking stemsAbove ground stems arise from rhizomesLack leaves and rootsSlide7

Phylum

Psilotophyta

– The Whisk Ferns

Structure

and

form cont’d.:

Sporophytes

: Enations - tiny, green, superficially leaflike, veinless, photosynthetic flaps of tissueRoots, aided by

mycorrhizal fungi, scattered along rhizomesSlide8

Phylum

Psilotophyta

– The Whisk Ferns

Reproduction:

Sporangia fused in

3s

and produced at tips of short

branchesGametophytes develop from spores beneath groundBranch dichotomouslyNo chlorophyllRhizoids aided by mycorrhizal fungi

Archegonia and antheridia scattered on

surfaceZygote develops foot and rhizome

Rhizome separates from footSlide9

Phylum

Psilotophyta

– The Whisk Ferns

Reproduction cont’d.:Slide10

Phylum

Psilotophyta

– The Whisk Ferns

Fossil whisk fern look-

alikes

Silurian, 400

myaCooksonia and RhyniaNaked stems and terminal sporangiaDevonian, 400-350

mya

ZosterophyllumNaked stems and rounded sporangia along stem

Thought to be ancestral to club mossesSlide11

Phylum

Lycophyta

– The Ground Pines, Spike Mosses, and

Quillworts

Collectively called club mosses

2 living major genera

Lycopodium

Selaginella2 living minor generaSeveral genera became extinct about 270

mya

Sporophytes have microphylls

Have true roots and stemsSlide12

Phylum

Lycophyta

Lycopodium

-

ground

pines

Often grow on forest floors

Stems simple or branchedDevelop from branching rhizomesLeaves usually < 1 cm long

Roots develop along rhizomesSlide13

Phylum

Lycophyta

Sporangia in axils of

sporophylls

- sporangium

-bearing leaves

Some species have sporophylls with no chlorophyll, are smaller than other leaves and clustered into strobili

(singular: strobus

)

In sporangia,

sporocytes

undergo meiosis, producing spores

Lycopodium

reproduction:Slide14

Phylum

Lycophyta

Lycopodium

reproduction cont’d.:

GametophyteSlide15

Phylum

Lycophyta

Selaginella

-

spike

mossesAbundant in tropicsBranch more freely than ground pinesLeaves with ligule on upper surfaceSlide16

Phylum

Lycophyta

Selaginella

reproduction:

Produce

2

different kinds of gametophytes = heterosporyMicrosporophylls bear microsporangia containing microsporocytes, producing tiny

microspores - becomes male gametophyte, consisting of

antheridium within microspore wall

Megasporophylls bear megasporangia

containing megasporocytes, producing 4 large

megaspores -develops into female gametophyte consisting of many cells inside megaspore

Several archegonia produced where spore wall

rupturesSlide17

Phylum

Lycophyta

Selaginella

reproduction cont’d.:Slide18

Phylum Lycophyta

Isoetes

-

quillworts

Found in

areas partially submerged in H2O for part of yearMicrophylls arranged in tight spiral on stubby stem

Ligules occur towards leaf

bases

Corms have vascular

cambium

Plants generally

> 10

cm

tallSlide19

Phylum

Lycophyta

Isoetes

reproduction:

Similar to spike mosses, except no

strobili

Sporangia at bases of leavesSlide20

Phylum

Lycophyta

Ancient relatives of club mosses and

quillworts

:

Dominant members of forests and swamps of Carboniferous, 325

myaLarge, tree-like, up to 30 meters tall - Lepidodendron

Surface of

Lepidodendron

, showing microphyll basesSlide21

Phylum

Equisetophyta

– The Horsetails and Scouring Rushes

Equisetum

Branched and

unbranched

forms, usually

> 1.3 m tall Stems jointed and ribbedIf branched, branches in whorls

Scalelike leaves in whorls at

nodesStomata in grooves between ribsSlide22

Phylum

Equisetophyta

Stem anatomy:

Hollow central cavity from break down of

pith

Two cylinders of smaller canals outside

pith

Carinal canals - conduct H2

O with xylem and phloem to outside

Vallecular canals - outside

carinal canals contain air

Silica deposits on walls of stem epidermal cellsSlide23

Phylum

EquisetophytaSlide24

Phylum

Equisetophyta

Equisetum

reproduction:

Asexual by fragmentation of rhizomes

Sexual reproduction:

Strobili

at tips of stems with sporangia connected to sporangiophoresSpores green with 4

elaters attached

Gametophytes lobed, green, cushion-like

, up to 8 mm in diameter

Spores with elatersSlide25

Phylum

Equisetophyta

Equisetum

reproduction cont’d.:Slide26

Phylum

Equisetophyta

Ancient relatives of horsetails:

Flourished in Carboniferous, 300

mya

Human and ecological relevance:

Many giant horsetails used for food by humans and other animalsScouring rush stems used for scouring and sharpening

Reconstruction of fossil giant horsetail,

CalamitesSlide27

Phylum

Polypodiophyta

– The Ferns

Structure and form:

Vary in size from tiny floating forms

< 1

cm to giant tropical tree ferns up to 25

m tallFern leaves are megaphylls - frondsTypically divided into smaller segments

Require external H2

O for reproductionSlide28

Phylum Polypodiophyta – The Ferns

Reproduction:

Sporophyte

conspicuous

phase

Fronds, rhizomes, roots

Fronds first appear coiled in crozier, and unroll and expandFronds

divided into segments called

pinnae (singular: pinna)

CrozierSlide29

Phylum

Polypodiophyta

– The Ferns

Reproduction cont’d.:

Sporangia

stalked

S

cattered on lower leaf surface, confined to margins, or found in discrete clusters called sori (singular: sorus)Sori may be protected by

indusia (singular: indusium

)With row of heavy-walled, brownish cells =

annulus

Sorus covered by indusiumSlide30

Phylum

Polypodiophyta

– The Ferns

Reproduction cont’d.:

Meiosis forms spores in

sporangia

Spores released and grow into gametophytes called

prothalli (singular: prothallus)

Prothalli one

cell thick, and have archegonia and antheridia

Zygote develops into young sporophyte

Gametophyte dies

and leaves sporophyte growing

independentlySlide31

Phylum Polypodiophyta – The Ferns

Reproduction cont’d.:Slide32

Phylum

Polypodiophyta

– The Ferns

Fossil relatives of ferns:

Devonian

, 375

mya - possible ancestors of ferns

Resemble ferns in growth habit, but look more like whisk ferns

Possible ancestors:

Aglaophyton

and

PsilophytonSlide33

Phylum Polypodiophyta – The Ferns

Fossil relatives of

ferns cont’d.

Carboniferous, 320-250

mya

- tree

ferns abundantSeeds found on some of fossil tree fernsSlide34

Phylum

Polypodiophyta

Human and ecological relevance:

House plants

Function well as air filters

Outdoor ornamentals

Cooked rhizomes as food

Folk medicineFronds used in thatching for houses.Basketry and weavingSlide35

Review

Introduction

Phylum

Psilotophyta

– The Whisk Ferns

Phylum

Lycophyta

– The Ground Pines, Spike Mosses and QuillwortsPhylum Equisetophyta – The Horsetails and Scouring RushesPhylum Polypodiophyta – The Ferns