22.3 Seed Plants

Apply Concepts Pollination is a process that occurs
only in seed plants. What process in seedless plants
is analogous to pollination
Review Describe how fertilization takes place in a
Classify Make a table with two columns labeled
haploid and diploid and assign each of the
following structures from the pine life cycle to the
appropriate column: Pollen tube, Seed cone, Embryo,
Ovule, Seedling
22.3 Seed Plants
The Importance of Seeds
Adaptations of seeds
 Plants
reproduce without open water
 Transfer of sperm by pollination
 Protection of embryos in seeds.
Plant embryo and a food supply encased in a
protective covering
Living plant within a seed is diploid and represents
the sporophyte phase.
Male gametophytes and the female gametophytes
grow and mature directly within the sporophyte
 Bear
seeds directly on the scales of cones
 Bear
seeds in flowers inside a layer of tissue that
protects the seed.
Pollen Grains
Contains entire male gametophyte
Carried to the female reproductive structure by
wind or animals
 Transfer
of pollen from the male reproductive structure
to the female reproductive structure.
Zygote contained within a seed grows into a tiny
plant- the sporophyte embryo
Embryo begins to grow under right conditions
Uses nutrients stored in the seed until it can carry out
photosynthesis on its own
Seed coat
 Surrounds
and protects the embryo and keeps the
contents of the seed from drying out.
Seed cones produce female gametophytes
Female gametophytes develop in two ovules at base
of scale.
Pollen cones produce pollen grains, which make up
the entire male gametophyte stage
One haploid nuclei will divide later to produce two
sperm nuclei.
Development Inside Seeds
Pollen tube
 Structure
containing two haploid sperm nuclei.
Development Inside Seeds
Pollen grain lands ovule
Splits open and begins to grow a pollen tube
Reaches the female gametophyte
 One
sperm nucleus disintegrates
 Other fertilizes the egg.
Fertilization produces a diploid zygote
Grows into an embryo.
Seed is an encased embryo that is ready to be
scattered by the wind and grow into a plant.
Reproduction in conifers occurs in cones from the
mature sporophyte plant.