1. PLANTS
Kingdom Plantae

2. Who Are The Plants?
Plants= eukaryotic,
multicellular,
photosynthetic

3. LAND PLANT EVOLUTION Monocot Eudicot Gymnosperms (Naked seeds)
Angiosperms
(Seeds in flowers and fruit)
Non-seeds
Seeds
Bryophytes
(Non-vascular)
Tracheophytes
(Vascular)
Green Algae

4. Origin of Land Plants? Evidence that Green Algae are the ancestors
1) DNA
2) Ch a & b
3) True starch inside chloroplasts
4) Diverse life cycles & reproduction
Asexual & sexual phases
Haploid & diploid stages

5. Green Algae as Land Plant Ancestors
(5) Unicellular
& multicellular
species

6. First land plants were probably filamentous green algae growing along the edges of ponds that seasonally dried out.
DNA evidence says land plants originated 500—600 mya.
First land plant fossils 470 mya

7. Which Land Plant is Most Like the Ancestral Green Alga ?
Green Algae
Mosses
Liverworts
Hornworts

8. Answer
Liverworts

9. Frist land plants were small and did not have vascular tissue.
They were bathed in water or lived in moist environments.
Called Bryophytes: moss, liverwort, hornwort.

10. LAND PLANT EVOLUTION Monocot Eudicot Gymnosperms (Naked seeds)
Angiosperms
(Seeds in flowers and fruit)
Non-seeds
Seeds
Bryophytes
(Non-vascular)
Tracheophytes
(Vascular)
Green Algae

11. Overview of Plant Kingdom
Land Plants

12. Important Characteristics
Presence or absence of vascular tissue
i.e. xylem and phloem
Bryophytes (mosses, liverworts, hornworts)
lack vascular tissue—small plants
Tracheophytes (ferns and seed plants)
have vascular tissue—can be large

13. What is vascular tissue?
Specialized cells that conduct fluids and nutrients from place to place in the organism
Xylem = cells specialized to carry
H20 & minerals
Phloem = cells specialized to carry
H2O & sugar

14. Characteristics of Plants
Xylem = cells specialized to carry
H20 & minerals
Phloem = cells specialized to carry
H2O & sugar

15. Characteristics of Plants
Xylem = cells specialized to carry
H20 & minerals
Phloem = cells specialized to carry
H2O & sugar

16. Characteristics of Plants
Life Cycles
Alternation of
Generations in
Land Plants

17. Characteristics of Plants
3. Life Cycles
Alternation of
Generations in
Land Plants

18. Characteristics of Plants
3. Life Cycles
Alternation of
Generations in
Land Plants
Both organisms are multicellular

19. Characteristics of Plants
Alternation of generations

20. 3 Challenges to living on land
Body dries out (desiccation)
Gravity collapses large organisms
Gametes dry out and may not disperse properly
How did the first land plants deal with these problems?
Let’s look at the moss life cycle.
They live in moist environments and they survive drying out—suspended animation

21. Look where mosses live

22. Look where mosses live

23. Look where mosses live

24. Haploid (gametophyte)
generation
is dominant
In bryophytes

25. Look at moss close up

26. Characteristics of Plants
Gametangia = gamete producing organs
Antheridium ♂ Swimming Sperm
Archegonium ♀ Eggs

27. Moss Sperm

28. Look at moss close up
Gametophyte Generation
Sporophyte Generation

29. Moss Life Cycle

31. How do sperm get to egg? Suggestions?
50% of moss species have different male and female plants that maybe several feet apart?
Suggestions?

32. Can rain spread sperm?
Experiment

33. Springtails crawl all over moss
Can insects be responsible for sperm dispersal?
Springtails crawl all over moss

34. Fertilization success
With insects vs. without insects.
With water spray vs.
without water spray
With insects & water
vs.
Without insects & water
Fertilization success in C. purpureus and B. argenteum microcosms, measured as the fraction of microcosms that developed sporophytes (error bars, mean ± s.e.m.). The effects of springtail treatment (a), water spray treatment (b) and the interaction between these treatments (c) on fertilization success. Plus and minus symbols represent the presence and absence of springtails and water spray. n = 108 microcosms. *P < 0.05.

35. Moss survive by
Living in moist environments and being able to become dormant when conditions are dry.
They are dependent upon moist conditions for reproduction because they have swimming sperm but they are aided by rain, mist, and fog and by animal transport of sperm.
Their dispersal over wide areas depends upon spores carried by the wind and animals

36. NEXT LECTURE: PLANT ADAPTATIONS