Lecture PowerPoint to accompany
Inquiry into Life
Twelfth Edition
Sylvia S. Mader
Chapter 29
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
29.1 Evolutionary History of Plants
• Plants evolved from algae over 500 million years
ago
• Characteristics plants and algae share
– Contain chlorophyll a and b and accessory pigments
– Store excess carbohydrates as starch
– Have cellulose in their cell walls
• Biochemical evidence shows plants are most
closely related to stonewarts, a type of green
algae
29.1 Evolutionary History of Plants
• Four Major Events in Evolution of Plants
– Development of embryo protection
– Development of vascular tissue
– Development of seeds
– Development of flowers
Evolutionary History of Plants
29.1 Evolutionary History of Plants
• Alternation of Generations
– All plants have a life cycle that included the
alternation of generations
• Sporophyte (2n)
• Gametophyte (n)
– Plants differ as to which generation is dominant (most
conspicuous)
Alternation of Generations
Reproduction in the Size of the
Gametophyte
29.2 Nonvascular Plants
• Nonvascular plants lack true roots, stems, and
leaves
– By definition, roots, stems, and leaves have vascular
tissue
• The gametophyte generation is dominant
• Three divisions
– Hornworts
– Liverworts
– Mosses
29.2 Nonvascular Plants
• Liverworts
– Two basic types: “leafy” and those with a flat, lobed
thallus
– Marchantia- thallus type
•
•
•
•
Smooth upper surface
Lower surface has many rhizoids which extend into soil
Reproduce both sexually and asexually
Asexual reproduction by gemmae- groups of cells that detach
and form new thallus
• Sexual reproduction by gametophores- structures that
produce gametes
Liverwort, Marchantia
29.2 Nonvascular Plants
• Mosses
– Found all over the world
– Mosses become dormant if the environment becomes
dry
– Most mosses can reproduce asexually by
fragmentation in addition to sexual reproduction
Moss Life Cycle, Polytrichum sp.
29.2 Nonvascular Plants
• Adaptations and Uses of Nonvascular Plants
– Can live on bare rock, fences, cracks of sidewalks
• Selective advantage to being small and simple
– Help convert rocks to soil
– Peat moss
• Used as fuel
• Holds water
• Used in gardens to improve soil
29.3 Seedless Vascular Plants
• Seedless vascular plants include whisk ferns,
club mosses, horsetails, and ferns
• The sporophyte is the dominant generation
• Vascular tissue
– Xylem
• Conducts water and minerals up from the soil
– Phloem
• Transports organic nutrients between parts of the plant
• Seedless vascular plants formed the swamp
forests of Carboniferous period
The Carboniferous Period
29.3 Seedless Vascular Plants
• Whisk FernsPsilophyta
– Arial stem with many forks
• Attached to rhizomeunderground stem
• No leaves, photosynthesis
occurs in stems
– Independent gametophyte
found underground
29.3 Seedless Vascular Plants
• Club Mosses
– Rhizome sends up
aerial stems
• Scale-like leaves
– Some are epiphytes
• Live on trees but do not
parasitize them
29.3 Seedless Vascular Plants
• Horsetails
– Moist habitats world wide
– Rhizome produces aerial
stems
– In some species, whorls of
side-branches come off the
main stem at regions called
nodes
– Leaves are scale-like
– Cones are at tips of stems
in most
– Have silica deposited in
cell walls
29.3 Seedless Vascular Plants
• Ferns
– Most abundant in warm, moist, tropical regions
– Leaves are called fronds
• Immature leaves are called fiddleheads
• Grow from rhizome
– Dominant sporophyte stage
• Produces wind-blown spores
– Spore germinates and forms small gametophyte
• Independent from the sporophyte
• Swimming sperm produced by antheridia
• Fertilization occurs in archegonia
Fern Life Cycle
Fern Diversity
29.4 Seed Plants
• Gymnosperms and Angiosperms
– Seeds contain a sporophyte embryo and stored food
within a protective coat
• This allows an embryo to survive during long periods of
dormancy
29.4 Seed Plants
• Gymnosperms
– Exhibit heterospory
• Two types of spores- produce two types of gametophytes,
male and female
• Pollen grains- male gametophyte
• Pollination-deposition of pollen on a female gametophyte
• Pollen tube-sperm pass through pollen tube to reach ovule
– No water required as it is in previous groups
• Female gametophyte develops within ovule
Pine Life Cycle
29.4 Seed Plants
• Gymnosperms
– Conifers are the most familiar gymnosperms
• Pines, spruces, firs, cedars, hemlocks, redwoods, and
cypress
• Adaptations and Uses of Conifers
– Adapted to cold, dry weather
– Pollen cones and seed cones are adaptations to land
– Needle-shaped leaves have small surface area to
decrease water loss
• Also have a thick cuticle and recessed stomata
– Wood is used in construction and for making paper
– Resins are used for production of chemicals
Conifers
29.4 Seed Plants
• Other Gymnosperms
– Cycads
• Resemble palms or ferns
• Pollen or seed cones grow on top of long vertical stem
• Plentiful in Mesozoic era at the time of dinosaurs
– Gingkoes
• Only one surviving species-Gingko biloba, the maidenhair
tree
• Female trees produce fleshy seeds that give off a foul odor
– Male trees are preferred for ornamental planting
– Gnetophytes
• Ephedra is only species in N. America
• Adapted to hot temperatures
Other Gymnosperms
29.4 Seed Plants
• Angiosperms
– Angio (vessel), sperm (seed)
– There are more known species of angiosperms than
all other types of plants combined
– Live in all types of habitats
– Seed develops from an ovule within an ovary
• Ovary becomes the fruit
– Two classes: Monocots and Eudicots
Flower Diversity
29.4 Seed Plants
• The Flower
– Flower parts
•
•
•
•
Receptacle: tip of stalk that bears flowers
Sepals: modified leaves that protect bud
Petals: modified leaves, may be colorful
Stamens: male reproductive structures
– Anther: pollen production
– Filament
• Carpels: female reproductive structures
– Stigma: for reception of pollen
– Style
– Ovary: ovule production
Generalized Flower
Flowering Plant Life Cycle
29.4 Seed Plants
• Life cycle, Adaptations, Uses of Flowering Plants
– Pollination can be by wind, water, insects, and other
animals such as bats
– Fruits, the final product of a flower aids in the
dispersal of seeds.
Fruits