Download 2. No vascular tissue

Introduction to Plants
What is a Plant?





Multicellular
Eukaryotic
Photosynthetic
Has cell walls
containing cellulose
Lacks mobility
What did they evolve from?

Green Algae

Similarities
contain chlorophyll
 have cell walls
made of cellulose
 store energy as
starch

Original Habitat

The simplest plants live surrounded by water
because water satisfies many of their needs:
 prevents
cells from drying out
 gives structural support
 provides nutrients
 helps with spore dispersal and meeting of sex cells

With time, plants adapted to live on land
Adaptations for Land
Adaptation
Definition
Advantage(s)
1. Cuticle
waxy coating on the
outer surface of
plant cells
prevents the cell from
drying out & acts as
a barrier to
pathogens
2. Stomata
openings in the outer enables exchange of
layer of leaves and gases for
some stems that
photosynthesis
allows the exchange
of gases
Adaptations for Land
Adaptation
Definition
Advantage(s)
3. Vascular Tissues
transport tissues that
move nutrients and
water throughout the
plant
faster transport than
with osmosis or
diffusion & provide
structure and support
for the plant
4. Reproductive
Strategies
adaptations that
allow sperm to meet
egg without water
(e.g. spores that have
waterproof
coverings, seeds)
enable plants to
reproduce without
being surrounded by
water
Plant Life Cycle



The lives of plants consist of two alternating stages,
or generations: a gametophyte generation and a
sporophyte generation.
The stage that produces gametes (sperm and eggs)
is the gametophyte generation. It is haploid.
The stage that produces spores is the sporophyte
generation. It is diploid.
Plant Life Cycle


One generation is
dominant over the other.
This means that it is
larger and lasts longer.
In most plants, the
diploid sporophyte
generation is dominant.
In mosses, the
gametophyte dominates.
How are Plants Classified?

No phyla, rather plants are organized into 12 divisions.
Non-Vascular Plants
Include mosses, liverworts, &
hornworts
1. Do not have true roots, stems
and leaves
- absorb water through cell
walls; water moves via osmosis.
2. No vascular tissue
- no xylem and phloem to
transport water and nutrients
Non-Vascular Plants
3. Small size
- no support from vascular
tissues
4. Depend on water for
reproduction
- water is needed for the
sperm to swim to the egg
Vascular Plants
1. Have true roots, stems and
leaves
2. Contain vascular tissue
- xylem transports water
- phloem transports food and
nutrients
- run continuously through the
roots, stems and the leaves
Vascular Plants
3. Larger size
- vascular tissues provide
support against gravity
4. Cuticle
- reduces water evaporation
from leaves and some stems
Seedless Plants


Most plants have
vascular tissue but may
or may not produce
seeds.
Ferns, horsetails, and
club mosses are seedless
vascular plants that
reproduce by spores.
Gymnosperms


Plants that reproduce by
seeds are divided into 2
groups: gymnosperms and
angiosperms.
Gymnosperms have "naked"
seeds usually protected by
cones. They include the
evergreens.
Angiosperms


Angiosperms are
flowering plants whose
seeds are produced
and protected within
fruit.
Further divided into
monocots and dicots.