Notes for seeded vascular plants - Gymnosperms and Angiosperms

1. Seed Plants
Gymnosperms & Angiosperms

2. Seeds
• Seeds are a major adaptation of land plants
that allow for reproduction without water
• As such, plants like gymnosperms and
angiosperms can be found in almost any
climate

3. Seeds
• A seed is an embryo (sperm & egg have fused)
– It contains a protective covering – seed coat
– It also has a food supply

8. Seeds
• Gymnosperms produce seeds inside of cones
• Angiosperms produce seeds inside of flowers

9. Pollen
• A pollen grain is often thought of as the
equivalent to a sperm cell, but it is actually the
entire male gametopyhte
• The sperm produced inside a pollen grain do
not swim, they are carried to the egg by wind,
insects or animals
– This is known as pollination

11. Cones
• Cones are the structures that gymnosperms
use to produce both male and female
gametophytes
• Male cones produce pollen
– Contains the “sperm” cells
• Female cones produce ovules
– Contains the egg cells

14. Pollination
• Pollen grains (gametophyte) are carried from
the male cone of one plant, to ovules
(gametopyhte) in the female cone of another
plant.
– Can be same plant, but not typically
• Once a gamete from the pollen grain meets
the egg inside the ovule, the two cells fuse,
eventually making an embryo inside of a seed.

15. Alternation of generations
• As with ferns, the sporophyte is the dominant
stage of the life cycle for gymnosperms.
• Trees like spruce, are the sporophyte, the
pollen grains and ovules formed inside of its
cones are the gametophyte

17. Gymnosperms
• Gymnosperms produce seeds that are
exposed or naked
– They have nothing covering them
– …unlike angiosperms that have a fruit surrounding
their seeds.

18. Angiosperms
• Unlike gymnosperms, their gametes, and
eventual seeds are made within flowers
• Whereas gymnosperms produce “naked”
seeds, angiosperms have their seeds
surrounded by a fruit

19. Flower Anatomy

20. Flower Anatomy

21. Stamen
• The stamen is the male structure of the
flowering plant
– Anther (makes pollen grains)
– Filament (holds anther)
• The pollen grain is the male gametophyte b/c
is makes the male gamete

22. Stamen

23. Flower Anatomy

24. Pistil/Carpel
• The pistil is the female structure of a
flowering plant
• The pistil may be made up of one or more
carpels
• The carpel consists of:
– 1 stigma
– 1 style
– 1 ovary

25. Pistil/Carpel

26. Pollination
• Pollination is the act of a pollen grain being
transport from the anther (male) to the
stigma (female) to allow for fertilization
– When this happens within the same flower it is
know as self-pollination
• Insects, birds, and wind are the most common
pollinators.

27. Fertilization
• Once the pollen grain lands on a stigma, the
male gametes inside still need to make it to
the female gametes in the ovules.
• A pollen tube burrows out from the grain, and
down through the style to the ovary and
ovules, delivering the sperm cell to the egg
cell for fertilization.
– Fertilization will result in an embryo within a seed!

28. Pollen tubes/Fertilization

33. Petals
• Petals are modified leave of the plants
• They protect the male and female
reproductive organs early on
• Usually brightly colored to attract pollinators
when the plant is mature

40. Fruits
• In biology, a fruit is anything that surrounds a
seed of a flowering plant
• The ovary, on fertilized becomes the fruit, just
as the fertilized ovules become the seeds.

45. Fruits?

46. Fruits?

47. Fruits
• The role of a fruit is to encourage animals to
eat them, so that seeds may be carried away
from where they were made
• They also serve as a form of added protection
in some cases.