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Wolodkowicz
Biology 1H
Plant Evolution & Classification
I.
II.
What is a plant? Kingdom Plantae includes over 350,000 species of
Eukaryotic, multicellular, land dwelling, photosynthesizing organisms.
A. What do plants have in common? Chloroplasts (contain
chlorophyll-pigment that traps light energy), undergo
photosynthesis (CO2 + H2O
C6H12O6 + O2), & a cell wall.
Plant Classification: Nonvascular plants and Vascular plants.
A. Nonvascular plants-The earliest, most primitive of plants. There
are 23,000 species. *Definition-plants that do not contain vascular
tissue (stems) (tube-like cells that carry water from the roots to the
leaves and food from the leaves to the roots), no true roots or
leaves.
1. Common characteristics: grow close to water and very
short.
2. Examples: Mosses and liverworts- small nonvascular
plants that contain a primitive stem and leaves, but no
roots.
a. Often found fixed to the ground or a tree trunk near
water.
b. Used as food for small animals (worms/snails, etc.)
3. Sphagnum moss- Found in bogs (acidic watery
environments). Due to acid environment, can preserve
organisms. After millions of years, sphagnum moss
becomes peat, which forms into coal.
4. Moss reproduction- Alternation of generations: One
generation uses sexual reproduction, and the next
generation uses asexual reproduction, etc. (refer to
handout).
B. Vascular plants- Plants that contain vascular tissue (tubes that carry
water from the roots throughout the plant and carry food from the
leaves down to the roots.
1. Characteristics: Size is not an issue due to its vascular
tissue, they do not have to be located near water, and they
can live in a variety of environments.
2. Major organs
a. Roots- anchor plants to the ground and take in water
and minerals from the soil.
b. Stem-composed of xylem and phloem. Xylem- is a
tube that carries water and minerals from the roots to
the leaves, and phloem carries food from the leaves to
Wolodkowicz
Biology 1H
the roots. Stem also holds up the leaves to the
sunlight.
c. Leaves- food production occurs here. Where most of
the chloroplasts are located.
3. Examples of vascular plants from most primitive to most
advanced (evolutionary terms)
a. Seedless vascular plants- reproduce via spores
(alternation of generation). Usually found in most
areas. Fern is an example. They have been around
form 300 million years. Leaves grow from an
underground stem in which the spores are found
underneath the leaves. Primitive root system.
b. Seeded plants: 2 types- Gymnosperms and the
angiosperms. Reproduce by forming seeds- plant
embryo (baby) plus a food source. (Sexual
reproduction)
1. Gymnosperms (conifers)- plants that produce
naked seeds in cones. These plants leaves
usually stay green all year round thus called
evergreens. Have been around for millions of
years. Ex: pine, spruce, fir, redwood, ect.
They can grow in all types of environments
and contain very hard wood. (3/4 of lumber in
the world).
2. Angiosperms (flowering plants)-majority of
plants (275,000 species). They contain protected
seeds, flowers and often fruits (protects the
seed and is used in seed dispersal via animals,
insects, wind, etc. (Grass, Maple trees, roses,
ect.)
a. Classification: Monocot or Dicots (majority
of flowering plants. Cotyledon-seed leaves.
# Of Cotyledons
Type of Venation
# Of Petals
Monocot
1
Parallel
In 3’s
Dicot
2
Net Venation
4’s or 5’s