Diversity of Plants and Fungi

BIO 101

Life Science

Dr. D. L. Daley

 

Evolutionary Tree of Plants

 

 

 

 

 

Overview of Plants

w  Non-vascular plants - (Bryophytes)

   18,600 species

   Liverworts, hornworts & mosses

w  Vascular plants (Tracheophytes) - internal tissues to conduct water and solutes through the roots, stems and leaves

   276,400 species

   Seedless vascular plants - ferns and horsetails

   Gymnosperms - Nonflowering seed plants - cycads, gingkos, conifers and gnetophytes

   Angiosperms - flowering seed plants

Bryophytes

w  Mosses, liverworts and hornworts

w  Non-vascular plants

w  No taller than 8 inches

w  They have leaflike, stemlike and rootlike parts but no xylem and phloem

w  Have rhizoids for underground absorption

Bryophytes

w   Have a cuticle to prevent water loss

w   Have cellular jacket around parts that produce eggs and sperm - holds in moisture

w   Archegonia - structures where the eggs develop

w   Antheridia - structures where sperm form

w   In some bryophytes the archegonia and antheria are located on the same plant - in other there are individual male and female plants

w   The sperm must swim to the egg through a film of water - in dry climates the reproduction must be times to coincide with the rains

Bryophytes

Hornworts

 

 

 

 

Mosses

w  Most common brytophyte

w  Grow in clusters

w  Most diverse and abundant group of bryophytes

w   Many mosses are able to survive the loss of much of the water in their bodies - they dehydrate and become dormant during dry periods

Peat Mosses

w  350 kinds

w  Commonly accumulates in bogs - many layers compressed

w  Peat bogs in cold and temperate regions of the world represents and area equal to 1/2 the united States

w  The peat moss secretes acids that inhibit bacterial and fungal breakdown

Why have vascular plants done so well?

1. Developed root systems - collect water and minerals from large area

2. Shoot systems - stems and leaves to absorb energy from sun and CO2 from the air

3. Cellular pipelines developed

Xylem - carries water & dissolved ions

Phloem - carries dissolved sugars and other photosynthetic products

4. Cuticle - waxy coat that helps the plants conserve water

Stomata - openings - control water loss and CO2 absorption

How Xylem Works

 

 

 

 

How Phloem works

 

 

 

 

Seedless Vascular Plants

w  Whisk Ferns - Psilophyta

   No roots only rhizomes - short mostly horizontal absorptive stems

w  Lycophytes - most familiar - club mosses

Seedless Vascular Plants

w   Horsetails - silica reinforced stems

w   Ferns - largest most diverse group

    Rust colored patches below the fronds of ferns - sorus - spore producing

Some Seedless Vascular Plants

Ferns

 

 

 

 

Seed-Bearing Plants

w   Dominate the land - aided by two adaptations

    Pollen and seeds

w   Pollen grains - tiny structures that carry the sperm producing cells

    Pollen grains are dispersed by wind or animal pollinators such as bees

    Pollen grains mean that these plants do not need water to carry the sperm to the egg such as in bryophytes

w   Seeds - embryonic plant, a food supply and a protective outer coat

    The seed coat keeps the embryo in a state of suspended animation or dormancy until proper conditions occur

Gymnosperms

w  Naked-seed - not enclosed in reproductive structure as in flowering plants

w  Conifers - scalelike or needlelike leaves - seeds exposed on cone scales

   Most abundant - pines

   Tallest - redwoods

   Oldest - bristlecone pines

s   4725 years old - sprouted when the Egyptians built the Great Sphinx

   Also includes firs , junipers, spruces and yews

Gymnosperms

w  Cycads

   Separate pollen bearing and seedbearing cones

   Leaves resemble palm trees

   Most subtropical or tropical

w  Ginkos

   Common in dinosaur times

   Only one survivor - maidenhair tree

w  Gnetophytes

   Woody plants

   Not very common

Gymnosperms

 

 

 

 

 

Angiosperms

w  Flowering, seed-bearing plants

w  Flowers are specialized reproductive structures

w  Angeion - means vessel - refers to the female reproductive parts at the center of the flower

w  Pollinators are insects, birds, bats and other animals - help transfer pollen to the female reproductive parts

w  260,000 species

Classes of Angiosperms

w  Monocots - one seed leaf

   Orchids, palms, lilies and grasses

w  Eudicots - two seed leafs

   Most herbaceous - such as cabbages and daisies

   Also flowering shrubs, trees (like oak and apple), water lilies and cacti

Monocots

 

 

 

Eudicots

 

 

 

 

Fungi

      A Fungus Is not a Plant

w  Heterotrophs - require organic compounds

w  They have filamentous bodies - slender filaments called hypae

   Form long chains of cells - connected by septa

   Mass of connected hypae - mycelium

w  Cells walls made of chitin - polysaccharide

Major Groups of Fungi

w  Zygomycetes

   e.g. Bread mold

w  Sac Fungi (Ascomycetes)

   Yeasts, common molds & morels and truffles

Major Groups of Fungi

w  Club Fungi (Basidiomycetes)

   Mushrooms, puffballs, toadstools and shelf fungi

Life Cycle of a Basidiomycetes

w  Mushroom (basidocarp) - short lived reproductive bodies

   The above ground part

w  Mycelium - lives below ground

   Extensive mesh of branched filaments

   Also called a primary mycelium

Life Cycle of a Basidiomycetes

w  Mushroom or basidocarp - stalk and a cap

   Gills line inner surface of cap

w  Gills

   Club-shaped spore bearing structures - basidium

   Spores - called basidospores

w  Basidospores land suitable site - mycelium forms

Life Cycle of a Basidiomycetes

w  Filament (hypha) of one strain meets another

   Cytoplasm fuses - not nuclei

   Secondary mycelium forms

s   Each cell has two nuclei - one from each strain

   Extensive mycelium forms

Life Cycle of a Basidiomycetes

w  Favorable conditions - get new mushroom

w  Each new mushroom - entirely of secondary mycelium

   Mushroom - composed of densely packed secondary mycelium

w  Two nuclei may fuse - get short-lived zygote

w  The zygote undergoes reduction division

w  Haploid spores (basidospores) form on small stalks - air currents disperse them

Life Cycle of a Typical Basidiomycetes

Fungal Diversity

w  Black bread mold - Rhizopus stolonifer

w  Common morel - sac fungi

w  Penicillium - sac fungi

   Roqueford cheese & antibiotics

w  Candidida albicans - yeast infection in humans

w  Athletes foot

A Fungus that is a Predator

Lichens

w  Symbionts - two species live together

w  Mutualism (both benefit)

w  Single vegetative body

   Fungal part (mycobiont) & photosynthetic species (photobiont)

w  13,500 species

w  Most are sac fungi & green algae or cyanobacteria

Structure of Lichen

Fungus largest component

Outer cortex of mycobiont

Below top cortex is the photobiont

Dispersal fragment can occur from top surface

Mycobiont & photobiont