Evolution
and Classification of land plants
Definition: Multicellular eukaryotic autotroph
With cell
walls made of cellulose
1.Phylum Algae: (used to be part of kingdom Plantae
Now it is
considered part of kingdom Protozoa)
-
Lives
in marine or aquatic environments
-
Uses
diffusion for gas exchange, to absorb
Minerals
-
It
uses swimming sperm and non motile eggs for
Sexual reproduction
a. Examples: Green algae, Red algae, Brown algae.
(seaweed)
Kingdom Plantae
2. Phylum Bryophyta – land plants
which are very delicate
They have no cuticle (protective waxy covering)
-
They
use diffusion for gas exchange
-
Use
swimming sperm and they have eggs
-
They
have gametophytes, which are
separate sexes
They have male and female gametophytes.
Sperm swim from males to females.
Examples: 1. Moss
2. Hornwort
3. liverwort
3. Phylum Tracheophyta – land plants
which have some of the following
characteristics
-
Have
a cuticle
-
Have
vascular tissue (conducting tubes which can deliver minerals,
Water, glucose)
-
Have
stomata – “breathing holes” for gas exchange
-
Are
much bigger than bryophytes
-
Examples
are
-
1. Subphylum Pterophyta – All ferns.
2. Subphylum Sphenophyta – Horsetails.
FERNS AND HORSETAILS HAVE SWIMMING SPERM
3. Subphylum Spermophyta – All plants which make
seeds
including trees of all kinds and including flowering plants.
SPERMOPHYTA DO NOT HAVE SWIMMING SPERM.
THEY MADE AN INNOVATION IN EVOLUTION: POLLEN
THEY DO NOT rely on water for SEXUAL REPRODUCTION.
-
They
all have vascular tissue – some extend
quite high up. Tall trees
-
All have cuticle, stomata.
-
A. “GYMNOSPERM GROUP” -
-
1. CLASS GINGKOAE – ginko
-
2. CLASS CONIFERAE – all evergreen trees
-
3. CLASS ANGIOSPERMAE – all plants that are
deciduous trees, AND ALL
-
FLOWERING
PLANTS.
THREE
EVOLUTIONARY TRENDS
1. EARLY PLANTS need water to sexually reproduce,
LATER PLANTS DON’T
SEXUAL REPRODUCTION REQUIRED sperm and egg in
early plants. Later plants used pollen, using wind. And the most recent plants use vector
pollination. ALTERNATION OF GENERATION
plants alternate between two generations. It is as if they use a different body form every other generation. For example, a male gametophyte mates with a female gametophyte and they create their offspring, a sporophyte. Then the sporophyte makes the next generation, gametophytes.
Imagine if you looked exactly like your grandparent and your child looked exactly like your parent
