Transcript A View of Life

Lecture 4: Chapter 24
Evolution and Diversity of Plants
Professor: Dr. Barjis
Room:
P313
Phone:
(718)2605285
Email:
[email protected]
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Alberts, Bray,
Sylvia S Mader
Hopkins,
Johnson
General Biology
Outline
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Evolutionary History
Alternation of Generations
Nonvascular Plants
Vascular Plants
– Seedless
– Seed
– Angiosperms
 Monocots and Eudicots
 Flowers
Evolutionary History of Plants
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Plants are thought to have evolved from
freshwater algae
Among the adaptations of plants to life on land
are:
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Protection of the embryo from drying out.
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Waxy cuticle on leaves to prevent drying out.
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Internal skeleton (in flowering plants) to
oppose gravity.
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Vascular system (in most plants) to move
water internally.
Other Terrestrial Adaptations
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Vascular tissue transports water and
nutrients to the body of the plant.
Cuticle provides an effective barrier to water
loss.
Stomata bordered by guard cells that
regulate opening, and thus water loss.
Plants
Based on the presence or absence of vascular tissue plants are divided into
vascular and non vascular plants. Liverworts and Mosses are examples of none
vascular plants.
Vascular
Non-vascular (bryophytes)
Based on the presence and absence of seeds vascular plants are classified into
plants with seed and plants without seed. Ferns are examples of plants without
seed.
Seedless
With seed
Based on the presence and absence of flowers, plants with seed are classified
into flowering and non-flowering plants. Conifers, Gingoes are examples of
non-flowering plants.
Flowering (Angiosperms)
Non-flowering (Gymnosperms)
Based on number of cotyledons and flower parts, flowering plants are classified
into Monocots and Eudicots
Monocots: One cotyledone, flower parts Eudicotes: Two cotyledon, flower
in 3 or multiple of 3, usually herbaceous, parts in 4 or 5 or multiples of 4 or 5,
usually parallel ventilation…
woody or herbaceous….
Four Major Plant Groups
Alternation of Generations
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Plant life cycle(s) include alternation of
generations cycle only.
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Sporophyte produces spores by the
process of meiosis and represents
diploid generation.
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Gametophyte produce gametes and
represents haploid generation.
Alternation of Generations
Alternation of Generations
Nonvascular Plants
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Nonvascular plants (bryophytes) lack
specialized means of transporting water and
organic nutrients.
Do not have true roots, stems, and leaves.
Produces eggs in archegonia
Produces flagellated sperm in antheridia
Nonvascular Plants
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Liverworts have either flattened thallus
(body) or leafy appearance with no true
root, no stem.
Asexualy reproduce by gemmae (group of
cells that detach from the thallus and can
start a new plant)
Figure 4: Gemma cup, Gemmae can detach and start a new plant
Nonvascular Plants
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Mosses usually have a leafy shoot.
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Can reproduce asexually by
fragmentation.
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Mosses prefer dump, moist and shaded
location, but could survive in deserts too
Vascular Plants
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They contain vascular tissue (Xylem and
Phloem).
Xylem transports water and dissolved
minerals up from roots.
Phloem transports sucrose and other
organic compounds throughout the plant.
Vascular plants are divided into plants with
seed and seedless plants
Seedless Vascular Plants
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Vascular seedless plants are
homosporous.
Ferns are example of seedless vascular
plant.
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Most abundant in warm, moist, tropical
regions,
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An egg is produced in an archegonium.
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A sperm is produced in an antheridium.
Seed Plants
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Vascular plants with seed are
heterosporous ( have two kind of spores)
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Microspores develop into pollen grain
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Megaspore develop into egg
Vascular plants with seed are classified
into Gymnosperms and Angiosperms
Gymnosperms
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Gymnosperms have ovules and seeds
exposed on the surface of sporophylls.
Examples of Gymnosperms are Conifers
and Ginkgoes
Conifers - bear cones
Ginkgoes - some trees produce seeds and
some produce pollen.
Pine Life Cycle
Pine Life Cycle
In the pine life cycle, female cones remain on the tree
over two years.
Angiosperms (flowering plants)
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Angiosperms are an exceptionally large and
successful group of plants.
live in all sorts of habitats, from fresh water
to desert, and from rigid north to the torrid
tropics.
Monocots and Eudicots
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Two classes of flowering plants.
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Monocotyledones (Monocots)
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Flower parts in three or multiple of
three.
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Usually parallel venation in leaves
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Eudicotyledones (Dicots)
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Flower parts in four or fives or
multiples of fours or five .
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Usually net venation
The Flower
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Flower consists of petals, sepals, stamen
(male reproductive organs) and carpel
(female reproductive organs).
Each stamen consists of an anther
(produce pollen) and a filament (stalk).
Carpel has three major regions.
 Ovary
 Style
 Stigma
Flowering Plant Life Cycle
Flowering Plant Life Cycle