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Chapter 16 - Plants, Fungi, and the Move
onto Land
• Terrestrial Adaptations - living on land poses
different problems from living in water
– Plants require structural specializations
• Roots and shoots
– Shoots
» Leaves – photosynthesis and gas exchange
» Stems – transport water up and sap down
– Roots – absorb water and dissolved minerals..
Leaves are main photosynthetic organs
Gametangia protect gametes
from dehydration; female
gametangia protect developing
embryos
Cuticle reduces water
loss
Stomata allow gas exchange
between plant and atmosphere
Lignin hardens cell walls
Whole alga performs
Photosynthesis;
absorbs water, CO2,
and minerals from the
water
Alga
Surrounding water
supports the alga
Shoot supports plant; may
perform photosynthesis
Vascular tissues transport
water, minerals, and sugars;
provide support
Roots anchor plant;
mycorrhizae (root/fungus
associations) help absorb
water and minerals from the
soil)
True root, stems, and leaves have vascular
tissue that form “veins” in the tissues.
•Xylem – transports water and minerals
through dead cells that form “straws” in
the tissue
•Phloem – living cells that transport sap
(sugars in water) throughout the plant..
Cenozoic
First seed plants
Early vascular plants
Origin of plants
Angiosperms
Gymnosperms
(e.g., conifers)
Seedless vascular plants
(e.g., ferns)
Bryophytes (e.g., mosses)
Charophyceans (a group of green algae)
Mesozoic
Diversity
Paleozoic
Plant
Diversification of
flowering plants
Nonvascular Plants – Bryophytes
•No vascular tissue, must be low to
ground, live in moist areas, no
true roots, stems, or leaves
Mosses – the most familiar..
• Plants, including mosses, have two distinct
versions of the plant
– The gametophyte,
which produces
gametes
– The sporophyte,
which produces
spores
(phyte = plant)..
• The life cycle of a moss exhibits an alternation of
generations
Gametes
(sperm and
eggs)
n
Spores
n
Gametophyte
n
Haploid
Fertilization
Meiosis
Diploid
Spore
capsule
Sporophyte
2n
Zygote
2n
Seedless Vascular Plants - Ferns
•Have vascular
tissue; true roots,
stems, and
leaves; do not
produce seeds;
have flagellated
sperm that swim
to ovule
Seed Plants – Gymnosperms & Angiosperms
Seed – embryonic plant with food supply
packaged in a protective coat..
Gymnosperms - Conifers
•Most all are
evergreens; produce
seed cones and
pollen cones;
sporophyte generation
is more prominent
than the gametophyte
generation..
• Pollen grain
– Is actually the much-reduced male
gametophyte
– Fertilizes the female gametophyte
• Ovule
– Contain the female gametophyte
– Will develop into the seed..
Angiosperms
– Supply nearly all our food and much of our fiber
for textiles
• More efficient water transport and the evolution of
the flower help account for the success of the
angiosperms
•A characteristic of angiosperms is double fertilization
•One sperm nucleus fertilizes and egg in the female
gametophyte = zygote
•One sperm nucleus fertilizes another cell in the female
gametophyte (not the egg) = endosperm
This synchronizes the development of the embryo and the
food reserves. The entire ovule develops in to a seed.
Female
gametophyte
Integuments
Spore case
Seed coat
(derived from
integuments)
Food supply
(derived from
female
gametophyte
tissue)
Spore
Haploid (n)
Pollen tube
Egg
nucleus
Pollen grain
(male gametophyte)
Discharged
sperm
nucleus
Embryo
(new sporophyte)
Diploid (2n)
(a) Ovule
(b) Fertilized ovule
(c) Seed..
Germinated pollen grain
(male gametophyte) on
stigma of carpel
Life cycle of
Angiosperms
Anther at tip of stamen
Pollen tube growing
down style of carpel
Mature
sporophyte
plant with
flowers
Ovary (base of
carpel)
Ovule
Fertilization
Embryo sac
(female
gametophyte)
Endosperm
Egg
Zygote
Sperm
nuclei
Sporophyte
seedling
Embryo
(sporophyte)
Seed
Germinating
seed
Seed
(develops
from ovule)
Fruit
(develops
from ovary)
Haploid (n)
Diploid (2n)..
• The dominant stage of the angiosperms is a
sporophyte with gametophytes in its flowers
Petal
Stamen
Pistil
Anther
Contains male
gametophyte =
pollen
Stigma
Filament
Style
Ovary
Ovule
Contains
female
gametophyte..
Sepal
Flower
•Sepals = outer whorl of modified leaves;
protection
•Petals = second whorl of modified leaves;
bright, showy; attract pollinators
•Stamen = anther & filament; produces pollen –
the male gametophyte
•Pistil = stigma, style, & ovary with ovules;
ovules contain the female gametophyte
Fruit = ripened ovary usually containing seeds..