Classification of organisms (incl. plants)

Two Types of organisms
Prokaryotes
No nucleus
No membrane-covered organelles
Circular DNA
Bacteria
Eukaryotes
Nucleus
Membrane-covered organelles (example: nuclear membrane)
Linear DNA
All other organisms
How they are the same: cytoplasm, ribosomes, DNA
Despite their differences they perform most of the same kinds of functions in the same way.

Endosymbiotic Theory: Origin of Eukaryotes
Cyanophora paradoxa: modern example of possible evolutionary process

Classification of Higher Plants
Non-flowering
Plants
Flowering
Spore-bearing
Naked seeds
No roots
with roots
Mosses
Ferns
Gymnosperms
1 seed-leaf
2 seed-leaves
Monocots
Dicots

1. Non-vascular plants
Division Bryophyta (mosses)
Division Hepatophyta (liverworts)
Division Anthocerophyta (hornworts)
2. Vascular plants
A. No seeds :
Division Lycopodiophyta (club mosses)
Division Monilophyta (ferns, horsetails, whisk ferns)
Class Psilotopsida- whisk ferns
Class Equisetopsida- horsetails
Class Polypodiopsida - ferns
B. Production of seeds :
1) No flowers : Gymnosperms
Division Pinophyta (Coniferophyta)- (conifers)
Division Cycadophyta (cycads)
Division Ginkgophyta (ginkgo)
Division Gnetophyta (gnetae)
2) Flowers : Angiosperms
Division Anthophyta (flowering plants)
Kingdom Plantae (embryophytes)

phylum Hepatophyta - liverworts
phylum Anthocerophyta - hornworts
phylum Bryophyta - mosses
Bryophytes
liverwort
hornwort
mosses

The bryophytes consist of about 20,000 plant species
Gametophyte dominant
Lack vascular tissues
Homosporous
Possess waterproof cuticle
Dispersal by windblown spores
Swimming sperm
Bryophyta

Mosses and their relatives are seedless nonvascular plants
Nonvascular plants grow close to the ground to absorb water and nutrients.
Seedless plants rely on free-standing water for reproduction.
Liverworts belong to phylum Hepatophyta.
often grow on wet rocks or in greenhouses
can be thallose or leafy

Hornworts belong to phylum Anthocerophyta
found in tropical forests and along streams
flat, lobed body with little green “horns”

Mosses belong to phylum Bryophyta.
most common seedless nonvascular plants
sphagnum moss commonly used by humans as “peat”

Life cycle of Marchantia

Moss Life cycle

Moss Protonema

Alternation of Generations: Mosses
leafy, haploid gametophyte with emerging diploid sporophyte

Division Lycopodiophyta (club mosses)
There are around 1,290 (Christenhusz & Byng 2016) living (extant) species of Lycopodiophyta
A vascular system allows club mosses to grow higher off the ground.
They need free-standing water for reproduction.
Club mosses belong to Lycopodiophyta.
not true mosses
oldest living group of vascular plants

Life cycle of Lycopodium

Homosporous vs. Heterosporous Plants
Homosporous
Sporophyte
Bisexual gametophyte
→
→
Single type of spore
eggs
sperm
Heterosporous
Sporophyte
Female gametophyte
megaspore
eggs
sperm
→
Male gametophyte
microspore
→

Life cycle of Selaginella

Division Equisetophyta (horsetails)
There are twelve living (extant) species of Equisetophyta.
Hosetails typically grow in wet areas, with whorls of needle-like branches radiating at regular intervals from a single vertical stem.
They need water conditions for reproduction.
Today horsetails are recognized as a group close relatives of the typical ferns (Pteridopsida).

Life cycle of Equisetum

Division Pterophyta: Ferns
Sporophyte dominant
Possess vascular tissues and roots
Leaves are megaphylls
Homosporous
Possess waterproof cuticle
Dispersal by windblown spores
Swimming sperm

Life cycle of Dryopteris

Life cycle of Marsilea

Alternation of Generations: Ferns
Ferns
Sporophyte = dominant (most conspicuous) individual
Gametophyte = small, fragile structure most people (even botanists!) never notice

Alternation of Generations: Ferns
Frond = diploid sporophyte
Sorus = collection of sporangia where meiosis occurs

Sori on a Fern Sporophyll

Sorus Close Up

Fern Sporangium

Fern Gametophytes

Alternation of Generations: Ferns
young diploid sporophyte beginning to grow from the haploid gametophyte

Ferns and their relatives belong to phylum Pteridophyta
whisk ferns and horsetails are close relatives of ferns
ferns have large leaves called fronds

Vascular Seed Plants
Gymnosperms
Nonflowering
Bear seeds on the upper surface of scales inside of cones
Contain true roots, stems, and leaves
Examples Conifers, Pines
Angiosperms
Flowering plants
Flower is a group of modified leaves used for sexual reproduction; seeds found in fruit
Contains true roots,stems, and leaves
Examples: rose, lily, oak, maple, pea, and grass

Seed plants include cone-bearing plants and flowering plants
Seed plants have several advantages over their seedless ancestors.
can reproduce without free-standing water, via pollination
pollination
occurs when
pollen meets
female plant
parts
seeds
nourish and
protect plant
embryo
seeds allow plants to disperse to new places

Gymnosperms
Leaves are needle-like
Most are evergreen
They are called soft wood.
Reproductive structure is a cone or cone-like structure.

Gymnosperms do not have seeds enclosed in fruit
most gymnosperms are cone-bearing and evergreen.
the cone is reproductive structure of most gymnosperms.
pollen is produced
in male cones.
eggs are produced in female cones.
seeds develop on scales of female cones.

Cycads are gymnosperms in phylum Cycadophyta
look like palm trees with large cones
grow in tropical areas
It includes about 130 species of tropical and subtropical evergreen low trees.

Ginkgos are gymnosperms in phylum Ginkgophyta
only one species alive today, Ginkgo biloba
grown in gardens and used in urban landscaping

Gnetophyta includes three relict genera: Gnetum, Welwitschia, and Ephedra
The primary difference between gnetophytes and other gymnosperms is the vessel elements similar to those found in flowering plants
Gnetophyta consists of about 70 species.

Conifers are gymnosperms in phylum Coniferophyta
All extant conifers are perennial woody plants.
The great majority are trees, though a few are shrubs.
They are the dominant plants over large areas of land, most notably the taiga in Northern Hemisphere.
It includes about 560 species of tropical and subtropical evergreen low trees.

Life Cycle of Gymnosperm

Diversity of Plants
Cone-bearing plants
760 species
Ferns and
their relatives
about 11,000 species
Mosses and
their relatives
20,000 species
Flowering
plants
235,000 species
Form 2 main groups nonvascular and vascular plants

Angiosperms
Broad leaf plants
Most are deciduous
Called hardwood
They are divided into two groups based on the number of seed leaves (cotyledons) they contain.

Haploid (N)
Diploid (2N)
MEIOSIS
FERTILIZATION
Ovule
Life Cycle of Angiosperms

Monocotyledons
“Monocots”
1 cotyledon
Parallel veins on leaves
Fibrous roots
Flowers in multiples of 3
Ex) grass, corn

Dicotyledons
“Dicots”
2 cotyledons
Netted veins
Tap root
Flowers, 4’s or 5’s
Ex) Peanuts, green beans

Linnaean System