Transcript Reproductive Structures

Plant Reproduction
Mostly About Reproductive Organs
in Plants - Chapter 8
Plant Kingdom
Gymnosperms - naked seeded plants don’t have flowers and don’t
use insects to transport pollen.
This group includes pines, junipers, bald cypress, cicadas,
podocarpus and the ginkgo tree.
Angiosperms - have flowers and often use insects to transport pollen.
Includes dicots and monocots.
Dicots – you know their characteristics
This group includes oaks, roses, blueberries, honeysuckle, cactus and
grapes.
Monocots – you know their characteristics
This group includes palms, grass, corn, orchids and bamboo.
Don’t forget that all plants
undergo “alternation of
generations” in their cycle of
existance. Each generation
alternates between the diploid
sporophyte and the haploid
gametophyte.
Reproductive Organs
Male or Pollen cones of
red pine (Pinus resinosa).
Early second year cone of
Knobcone Pine (Pinus
attenuata).
This is the female cone of a
Gymnosperm,
Flowers (dicot)
Monocot flower.
Complete flowers have sepals, petals, stamens, and pistils. Flower #1 is a complete
flower.
Incomplete flowers are missing one of more of the four basic parts. Flowers #2 &
#3 are incomplete.
Perfect flowers have both stamens and pistils. Flower #1 is a perfect flower.
Imperfect flowers have either stamens or pistils, but not both. Flower #3 is an
imperfect flower.
Staminate flowers have only stamens.
Pistillate flowers have only pistils.
Monoecious plants have imperfect flowers with both sexes growing on the same
plant.
Dioecious plants have imperfect flowers with only one sex growing on each plant.
Complete
Flower
female
Incomplete
Flower
male
Pollination
• Wind – simple, plain,
w/o nectar
• Vector pollination –
large, fragrant,
showy, w/ nectar
Other adaptations to help aide
or encourage pollination
•
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•
•
•
Platforms (petal clusters)
Nocturnal
Devices (hammerback)
Opening size
Special scents
Self-pollination is less adaptive
Cross pollination is favored
• Male flowers below female flowers
• Male flower matures before female
flowers
• Anthers mature first in complete flowers
• Stigma longer than stamens
Pollen.
Pollinators
Pollination
does NOT equal
Fertilization
Transfer of pollen
is NOT the
joining of egg and sperm
Fertilization
Fertilization
Seed formation
•
•
•
•
Post fertilization
Wall of ovule = hard seed coat
Zygote divides = embryo
Triploid central cell = endosperm
• Many arctic plants
cannot flower until the
length of day light
hours has reached at
least a minimum value
(long day plants). This
means that warmer
temperatures will not
result in early
flowering of the
species, as it is
dependent on light
hours. Many
temperate zone plants
are short-day plants,
where the shorter days
of fall act as a trigger
for flowering.
• Most plant species are day-neutral plants,
which means their blooming times are
controlled by temperature, moisture, or
environmental factors other than day
length
Seeds
Cones of
(clockwise
from top-left):
Loblolly Pine
(Pinus taeda)
Jack Pine
(Pinus
banksiana)
Gray Pine
[with seeds]
(Pinus
sabiniana)
Knobcone
Pine (Pinus
attenuata
Gymnosperm seed.
Dicot seed.
Monocot seed
Fruit Development
• Ovary enlarges and
ripens
• Seeds contained
within
• Dry or fleshy
Do you know fruits from
vegetables?
Seed Dispersal
Seed Germination
Summary
Asexual Reproduction
• Vegetative reproduction
• From some vegetative organ rather than
from the flower
• Includes roots, stems, leaves
• Part takes root and grows into a “clone”
of the parent plant
• Strawberries and spider plants produce
runners over the ground, irises and ferns
produce rhizomes underground, daffodils
and hyacinths produce daughter bulbs
and potatoes produce daughter tubers.
Plant Hormones
Plant Growth
Growth
• Meristem tissue - source of new cells in
plant growth
• apical meristem - produce growth in length
(primary growth)
lateral meristem - produce growth in
thickness (secondary growth)
• Primary Growth: the growth initiated by
the apical meristems of a plant or shoot.
Basically what is meant by this term is
the initial new growth of the plant stem
and root. The parts of the stem and root
which are the primary growth are mostly
the very ends where the most growth is
taking place and will take place.
• Secondary Growth: the increase in girth
of the stems and roots of many plants,
especially woody, perennial dicots. This
occurs in plants such as a tree. When the
plant grows it not only becomes taller but
also the width or girth of the tree grows
too. Obviously this is what is described as
secondary growth.
Tropisms –
growth
responses by
plants to
their
environment