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1. Terrestrial adaptation of plants
1. Apical meristems
•Apical meristems are localized areas of
cell division at tips of roots and shoots.

2. 2. Evolution of parenchyma
3. Multicellular, dependent embryos
a. Embryo develops within female tissue; female
plant provides nutrition (sugars, proteins).

Terrestrial adaptation of plants

3. b. Placental transfer cells that enhance
the transfer of nutrients from the parent
to the embryo.
Terrestrial adaptation of plants

4. 4. Alternation of generations: Two
multicellular body
forms
a. Gametophyte (haploid) that produces
gametes. Gametes fuse to form zygotes
that develop into embryo
b. Sporophytes (diploid) that produce
spores. Spores are haploid cells that can
develop into a new organism without
fusing with another cell.
Terrestrial adaptation of plants

5. Terrestrial adaptation of plants

6. 5. Spore walls contain
sporopollenin
a. Sporopollenin is a polymer that makes the walls of
plant spores very tough and resistant to harsh
conditions.
b. Sporopollenin is the most durable organic material
known.

c. Spores are produced by sporangia (cells in the
sporophyte) through the process of meiosis.
d. Durable spores are an adaptation for surviving on
land. Can withstand long periods of adverse
conditions. Easily transported by wind and water.
Terrestrial adaptation of plants

7. Terrestrial adaptation of plants

8. 6. Multicellular gametangia

a. Gametangia are the gametophyte forms of
bryophytes, pteridophytes, and gymnosperms.
Gametes are produced within these organs.

b. Female gametangia are called archegonia à
(produce and retain egg cells)
c. Male gametangia are called antheridia à
(produce sperm)
Terrestrial adaptation of plants

9. Terrestrial adaptation of plants

10. 7. Other terrestrial adaptations common
to many land plants

a. Epidermis covered by a waxy cuticle to
prevent excess loss of water. Pores
(stomata) in cell layer can be opened and
closed to allow O
2
out and CO
2
in.

11. Terrestrial adaptation of plants

12. 8. Except for bryophytes, land plants have
vascular tissue in roots, stems, and leaves.

- Xylem consists of dead cells that carry water
and nutrients from roots to the rest of the
plant.

- Phloem consists of living cells that distribute
sugars and amino acids throughout the plant.

Terrestrial adaptation of plants

13. Terrestrial adaptation of plants

14. Origin of land plants

1.Theory is that land plants evolved from
charophycean algae over 500 million
years ago.
•Charophycean algae inhabit shallow
waters and need to survive when water
levels drop. Lead to increasing ability to
survive entirely on dry land.

15. •Chareophycenaceae (green algae) are closer to green
plants, might be the ancestors of land plants
ØGreen algae and land plants have common ancestor
v recent studies show that Zygnematales as the
closest living relatives
vZygnematales is an order of green algae that include
the common Zygnema and Spirogayra
Origin of land plants

16. 2. Alternation of generations in plants may have
originated by delayed meiosis

•Zygote à Sporophyte à Many, many spores
a. Occurs on land because it’s more difficult to
produce zygotes. (No water for swimming sperm)

b. By producing sporophyte, many gametophytes
can be produced from one zygote because many,
many spores are produced. This maximizes
output of sexual reproduction.
Origin of land plants

17. •Some charophyceans are haploid organisms.
Ø They lack a multicellular sporophyte, but the
zygotes are retained and nourished on the parent.
•The zygote of a charophyceans undergoes
meiosis to produce haploid spores, while the
zygote of a land plants undergoes mitosis to
produce a multicellular sporophyte.
ØThe sporophyte then produces haploid spores by
meiosis.
Origin of land plants

18. Origin of land plants

19. Origin of land plants