The document summarizes key aspects of plant biodiversity, including: 1. There are over 290,000 known plant species that provide oxygen, food, and stabilize landscapes. 2. Land plants enabled survival of other organisms on land through traits like roots and alternation of generations. 3. Plants are grouped based on presence of vascular tissue, with seed plants dominating due to advantages of seeds over spores.

1. UNIT 3:
BIODIVERSITY
OF PLANTS
Campbell & Reece (2010);
Chapter 29 and 30
http://en.wikipedia.org/wiki/File:Diversity_of_
plants_image_version_2.png

2. 290, 000 known plant species
Land plants enabled survival of other life
forms on land – including animals
Roots provide habitats, stabilize landscapes
Oxygen supply
Ultimate provider of food eaten by terrestrial
animals

3. Common (derived) traits of land plants –
separate them from ancestral plants (algal
relatives):
Alternation of generations & multicellular,
dependent embryo’s
Walled spores produced in sporangia
Multicellular gametangia
Apical meristems

4. Alteration of Generations
The life cycle includes both
multicellular haploid (n) &
multicellular diploid (2n)
organisms

5. Multicellular, Dependent Embryos
After fertilization zygote develops into
a multicellular embryo within maternal
structures.
Maternal tissues provide nutrients.
Embryo is dependent
Land plant called embryophytes.

6. Walled Spores Produced in Sporangia
Sporophyte produces spores in organs called
sporangia
Diploid cells called sporocytes undergo
meiosis – generate (n) spores
Spore walls contain
sporopollenin:
resistant to harsh
environments

7. Multicellular Gametangia
Gametes produced in multicellular organs – gametangia.
Female gametangia – archegonia – produce single egg
Male gametangia – antheridia - produce & release sperm
– fertilize egg internally
within the archegonium

8. Apical Meristems
Plants sustain continual growth in
apical meristems
Cells from apical meristems differentiate into various
tissues
1) Elongation of the roots
Nutrients & water from soil
2) Growth of stems & leaves
More area for photosynthesis

9. GROUPING OF LAND PLANTS
• Ancestral species gave rise to a vast diversity of
modern plants
• Land plants informally grouped based on
presence or absence of vascular tissue
• Most plants have vascular tissue; these
constitute the vascular plants
• Nonvascular plants are commonly called
bryophytes
sites.google.com

10. GROUPING OF LAND PLANTS
• Seedless vascular plants can be divided:
– Lycophytes (club mosses and their relatives)
– Pterophytes (ferns and their relatives)
contrib.andrew.cmu.edu
quizlet.com
en.wikipedia.org
biology.iastate.edu

11. GROUPING OF LAND PLANTS
• Seed plants
• A seed is an embryo and nutrients surrounded by
a protective coat
• Seed plants can be divided into:
– Gymnosperms, the “naked seed” plants, including
the conifers
– Angiosperms, the flowering plants

12. GYMNOSPERMS ANGIOSPERMS
visual.merriam-webster.com
bluebellnursery.com
• Conifers (seeds not enclosed)
• “Naked seed”
• All flowering plants
• 90% of living plant species
• Seeds develop in ovaries –
originate within flowers & mature
into fruits
biology.iastate.edu
ucadia.com

13. Bryophyta (non-vascular plants)
(p. 606 – 609)
• Phylum includes all mosses (Bryophyta)
• Bryophytes: all non-vascular plants
– Include liverworts, hornworts & mosses
• Mosses show alteration of generations
– i.e. have sporophyte & gametophyte generation
tolweb.orgflickrhivemind.netbryophytes.plant.siu.edu anbg.gov.au forums.gardenweb.com

14. Bryophyta
• In all bryophytes gametophytes are dominant
in life cycle
• Larger & longer living than sporophyte
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botany.hawaii.edu

15. Key
Haploid (n)
Diploid (2n)
Protonemata
(n)
“Bud”
“Bud”
Male
gametophyte
(n)
Female
gametophyte (n)
Gametophore
Rhizoid
Spores
Spore
dispersal
Peristome
Sporangium
MEIOSIS Seta
Capsule
(sporangium)
Foot
Mature
sporophytes
Capsule with
peristome (SEM)
Female
gametophytes
2mm
Raindrop
Sperm
Antheridia
Egg
Archegonia
FERTILIZATION
(within archegonium)
Zygote
(2n)
Embryo
Archegonium
Young
sporophyte
(2n)
THE MOSS LIFE CYCLE
D:Chapter_29A_PowerPoint_Lectures29_Lecture_Presentation29_13FernLifeCycle_A.html

16. Key
Haploid (n)
Diploid (2n)
Protonemata
(n)
“Bud”
“Bud”
Male
gametophyte
(n)
Female
gametophyte (n)
Gametophore
Rhizoid
Spores
Spore
dispersal
Peristome
Sporangium
MEIOSIS Seta
Capsule
(sporangium)
Foot
Mature
sporophytes
Capsule with
peristome (SEM)
Female
gametophytes
2mm
THE MOSS LIFE CYCLE

17. Key
Haploid (n)
Diploid (2n)
Protonemata
(n)
“Bud”
“Bud”
Male
gametophyte
(n)
Female
gametophyte (n)
Gametophore
Rhizoid
Spores
Spore
dispersal
Peristome
Sporangium
MEIOSIS Seta
Capsule
(sporangium)
Foot
Mature
sporophytes
Capsule with
peristome (SEM)
Female
gametophytes
2mm
Raindrop
Sperm
Antheridia
Egg
Archegonia
FERTILIZATION
(within archegonium)
THE MOSS LIFE CYCLE

18. Key
Haploid (n)
Diploid (2n)
Protonemata
(n)
“Bud”
“Bud”
Male
gametophyte
(n)
Female
gametophyte (n)
Gametophore
Rhizoid
Spores
Spore
dispersal
Peristome
Sporangium
MEIOSIS Seta
Capsule
(sporangium)
Foot
Mature
sporophytes
Capsule with
peristome (SEM)
Female
gametophytes
2mm
Raindrop
Sperm
Antheridia
Egg
Archegonia
FERTILIZATION
(within archegonium)
Zygote
(2n)
Embryo
Archegonium
Young
sporophyte
(2n)
THE MOSS LIFE CYCLE
D:Chapter_29A_PowerPoint_Lectures29_Lecture_Presentation29_13FernLifeCycle_A.html

19. VASCULAR PLANTS
LIVING VASCULAR PLANTS CHARACTERISED BY:
• Life cycles with dominant sporophytes
– Fern life cycle
• Transport in vascular tissues
– Xylem and phloem
• Well-developed roots and leaves
– Including spore bearing leaves called sporophylls

20. Pterophyta
(p. 610 – 615)
• Phylum includes all ferns, horsetails & whisk ferns
• Vascular seedless plants
– Vascular means plants could grow taller than bryophytes
• Ferns show alteration of generations (dominant sporophyte)
• Sperm flagellated – must swim through water to reach eggs
i.e. found in damp environments
tolweb.orgflickrhivemind.netbryophytes.plant.siu.edu forums.gardenweb.com
botany.hawaii.edu

21. Key
Haploid (n)
Diploid (2n)
MEIOSIS
Spore
dispersal
Sporangium
Sporangium
Mature
sporophyte
(2n)
Sorus
Fiddlehead
Spore
(n)
Young
gametophyte
Mature
gametophyte
(n) Archegonium
Egg
Antheridium
Sperm
FERTILIZATION
New
sporophyte
Gametophyte
Zygote
(2n)
THE FERN LIFE CYCLE
D:Chapter_29A_PowerPoint_Lectures29_Lecture_Presentation29_13FernLifeCycle_A.html

22. Key
Haploid (n)
Diploid (2n)
MEIOSIS
Spore
dispersal
Sporangium
Sporangium
Mature
sporophyte
(2n)
Sorus
Fiddlehead
THE FERN LIFE CYCLE

23. Key
Haploid (n)
Diploid (2n)
MEIOSIS
Spore
dispersal
Sporangium
Sporangium
Mature
sporophyte
(2n)
Sorus
Fiddlehead
Spore
(n)
Young
gametophyte
Mature
gametophyte
(n) Archegonium
Egg
Antheridium
Sperm
FERTILIZATION
THE FERN LIFE CYCLE

24. Key
Haploid (n)
Diploid (2n)
MEIOSIS
Spore
dispersal
Sporangium
Sporangium
Mature
sporophyte
(2n)
Sorus
Fiddlehead
Spore
(n)
Young
gametophyte
Mature
gametophyte
(n) Archegonium
Egg
Antheridium
Sperm
FERTILIZATION
New
sporophyte
Gametophyte
Zygote
(2n)
THE FERN LIFE CYCLE
D:Chapter_29A_PowerPoint_Lectures29_Lecture_Presentation29_13FernLifeCycle_A.html

25. Transport in Vascular Tissues
• Two types of vascular tissue:
• Xylem and phloem
• Xylem conducts water & minerals
• Dead cells called tracheids
• Phloem distributes sugars, amino acids, & other organic
products
• Consists of living cells
• Water-conducting cells are strengthened by lignin
and provide structural support

26. Evolution of Roots
• Benefits of lignified vascular tissue below
ground
• Instead of rhizoids, roots evolved
– May have evolve from subterranean stems
• Roots: organs to absorb water & nutrients
from soil
• Also anchor vascular plants

27. Evolution of Leaves
• Leaves increase surface area of plant body
• Main photosynthetic organ of vascular plants
• Classified as:
– Microphylls (only lycophytes) – leaves with a
single vein
– Megaphylls (all vascular plants) – highly branched
vascular system
• Greater photosynthetic productivity

28. Evolution of Leaves
According to one model of evolution, microphylls evolved first, as
outgrowths of stems

29. Sporophylls and Spore Variations
• Sporophylls are modified leaves with
sporangia
• Sori are clusters of sporangia on the
undersides of sporophylls
• Strobili are cone-like structures
formed from groups of sporophylls

30. • Most seedless vascular plants are homosporous
• Produce one type of spore that develops into a bisexual
gametophyte
• All seed plants (and some seedless vascular plants)
are heterosporous
• Produce megaspores that give rise to female
gametophytes
• And microspores that give rise to male gametophytes
Sporophylls and Spore Variations

32. SEED PLANTS
• Seeds changed the course of plant evolution
– Plants with seeds would become dominant
producers in most terrestrial ecosystems
• Living seed plants can be divided into two:
– Gymnosperms
– Angiosperms
• A seed consists of an embryo and nutrients
surrounded by a protective coat

33. SEED PLANTS
5 DERIVED TRAITS: (COMMON TO ALL SEED PLANTS)
1. Reduced gametophytes
– Develop in walls of spores that are retained in tissues of
parent sporophyte
2. Heterospory
– Megasporangia produce megaspores (female
gametophytes)
– Microsporangia produce microspores (male
gametophytes)

35. SEED PLANTS
3. Ovules
– An ovule consists of a megasporangium, megaspore, and
one or more protective integuments
• Gymnosperm megaspores have one integument
• Angiosperm megaspores usually have two integuments

36. SEED PLANTS
4. Pollen
– Microspores develop into pollen grains – contain male
gametophytes
– Pollination is the transfer of pollen to the part of a seed
plant containing the ovules
 Pollen eliminates need for film of water
 Can be dispersed great distances by air or animals
 If a pollen grain germinates, it gives rise to a pollen tube
that discharges two sperm into the female gametophyte
within the ovule

38. SEED PLANTS
5. Seeds
• Evolutionary
advantages over
spores:
– May remain dormant
for days to years, until
conditions are favorable
for germination
– Transported long
distances by wind or
animals

39. Seed coat
(derived from
integument)
(c) Gymnosperm seed
Embryo (2n)
(new sporophyte)
Food supply
(female
gametophyte
tissue) (n)
(b) Fertilized ovule(a) Unfertilized ovule
Integument
Immature
female cone
Spore wall
Megasporangium
(2n)
Male gametophyte
(within a germinated
pollen grain) (n)
Megaspore (n) Micropyle Pollen grain (n)
Egg nucleus (n)
Discharged
sperm nucleus (n)
Female
gametophyte (n)

40. SUMMARY

41. Gymnosperms
(p. 618 – 625)
• Plants with ‘naked seeds’ not enclosed in
ovaries
• Include conifers (pine tree) and cycads
• Three key features of the gymnosperm life cycle
are:
1. Dominance of the sporophyte generation
2. Development of seeds from fertilized ovules
3. The transfer of sperm to ovules by pollen
• The life cycle of a pine provides an example
tolweb.orgflickrhivemind.netbryophytes.plant.siu.edu forums.gardenweb.com
botany.hawaii.edu

42. Microsporangium (2n)
Microsporocytes
(2n)
Pollen
grains (n)
Pollen
cone
Microsporangia
MEIOSIS
Mature
sporophyte
(2n)
Haploid (n)
Diploid (2n)
Key
MEIOSIS
Surviving
megaspore (n)
Pollen
grain
Megasporocyte (2n)
Ovule
Integument
Ovulate
cone
FERTILIZATION
Pollen
tube
Female
gametophyte
Sperm
nucleus (n)
Egg nucleus (n)
Archegonium
Seedling
Seeds
Seed coat
(2n)
Food
reserves
(n)
Embryo
(2n)
Megasporangium
(2n)
THE PINE LIFE CYCLE
D:Chapter_30A_PowerPoint_Lectures30_Lecture_Presentation30_06PineLifeCycle_A.html

43. Microsporangium (2n)
Microsporocytes
(2n)
Pollen
grains (n)
Pollen
cone
Microsporangia
MEIOSIS
Mature
sporophyte
(2n)
Haploid (n)
Diploid (2n)
Key
Ovulate
cone
THE PINE LIFE CYCLE

44. Microsporangium (2n)
Microsporocytes
(2n)
Pollen
grains (n)
Pollen
cone
Microsporangia
MEIOSIS
Mature
sporophyte
(2n)
Haploid (n)
Diploid (2n)
Key
MEIOSIS
Surviving
megaspore (n)
Pollen
grain
Megasporangium
(2n)
Megasporocyte (2n)
Ovule
Integument
Ovulate
cone
THE PINE LIFE CYCLE

45. Microsporangium (2n)
Microsporocytes
(2n)
Pollen
grains (n)
Pollen
cone
Microsporangia
MEIOSIS
Mature
sporophyte
(2n)
Haploid (n)
Diploid (2n)
Key
MEIOSIS
Surviving
megaspore (n)
Pollen
grain
Megasporocyte (2n)
Ovule
Integument
Ovulate
cone
FERTILIZATION
Pollen
tube
Female
gametophyte
Sperm
nucleus (n)
Egg nucleus (n)
Archegonium
Megasporangium
(2n)
THE PINE LIFE CYCLE

46. Microsporangium (2n)
Microsporocytes
(2n)
Pollen
grains (n)
Pollen
cone
Microsporangia
MEIOSIS
Mature
sporophyte
(2n)
Haploid (n)
Diploid (2n)
Key
MEIOSIS
Surviving
megaspore (n)
Pollen
grain
Megasporocyte (2n)
Ovule
Integument
Ovulate
cone
FERTILIZATION
Pollen
tube
Female
gametophyte
Sperm
nucleus (n)
Egg nucleus (n)
Archegonium
Seedling
Seeds
Seed coat
(2n)
Food
reserves
(n)
Embryo
(2n)
Megasporangium
(2n)
THE PINE LIFE CYCLE
D:Chapter_30A_PowerPoint_Lectures30_Lecture_Presentation30_06PineLifeCycle_A.html

47. Angiosperms
(p. 625 – 634)
• Most widespread and diverse of all plants
• Are seed plants with reproductive structures
called flowers and fruits
• Characterised by enclosed seeds
• The flower is an angiosperm structure
specialized for sexual reproduction
• Pollinated by insects, animals or wind

48. Angiosperms
(p. 625 – 634)
• A flower is a specialized shoot with up to four
types of modified leaves:
– Sepals, which enclose the flower
– Petals, which are brightly colored and attract
pollinators
– Stamens, which produce pollen on their terminal
anthers
– Carpels, which produce ovules
• A carpel consists of an ovary at the base and a style
leading up to a stigma, where pollen is received

50. Angiosperms
(p. 625 – 634)
• A fruit typically consists
of a mature ovary but
can also include other
flower parts
• Fruits protect seeds and
aid in their dispersal
• Mature fruits can be
either fleshy or dry

51. Angiosperms
(p. 625 – 634)
• Various fruit
adaptations help
disperse seeds
• Seeds can be carried by
wind, water, or animals
to new locations

52. MEIOSIS
Key
Microsporangium
Microsporocytes (2n)
Generative cell
Anther
Tube cell
Pollen
grains
Microspore
(n)
Male gametophyte
(in pollen grain)
(n)
Mature flower on
sporophyte plant
(2n)
Haploid (n)
Diploid (2n)
MEIOSIS
Ovule (2n)
Ovary
Megasporangium
(2n)
Megaspore
(n)
Female gametophyte
(embryo sac)
Antipodal cells
Central cell
Synergids
Egg (n)
Pollen
tube
Pollen
tube
Stigma
Sperm
(n)
Discharged sperm nuclei (n)
FERTILIZATION
Germinating
seed
Embryo (2n)
Endosperm (3n)
Seed coat (2n)
Seed
Nucleus of
developing
endosperm
(3n)
Zygote (2n)
Egg
nucleus (n)
Style
Sperm
THE ANGIOSPERM LIFE CYCLE

53. MEIOSIS
Key
Microsporangium
Microsporocytes (2n)
Generative cell
Anther
Tube cell
Pollen
grains
Microspore
(n)
Male gametophyte
(in pollen grain)
(n)
Mature flower on
sporophyte plant
(2n)
Haploid (n)
Diploid (2n)
THE ANGIOSPERM LIFE CYCLE

54. MEIOSIS
Key
Microsporangium
Microsporocytes (2n)
Generative cell
Anther
Tube cell
Pollen
grains
Microspore
(n)
Male gametophyte
(in pollen grain)
(n)
Mature flower on
sporophyte plant
(2n)
Haploid (n)
Diploid (2n)
MEIOSIS
Ovule (2n)
Ovary
Megasporangium
(2n)
Megaspore
(n)
Female gametophyte
(embryo sac)
Antipodal cells
Central cell
Synergids
Egg (n)
THE ANGIOSPERM LIFE CYCLE

55. MEIOSIS
Key
Microsporangium
Microsporocytes (2n)
Generative cell
Anther
Tube cell
Pollen
grains
Microspore
(n)
Male gametophyte
(in pollen grain)
(n)
Mature flower on
sporophyte plant
(2n)
Haploid (n)
Diploid (2n)
MEIOSIS
Ovule (2n)
Ovary
Megasporangium
(2n)
Megaspore
(n)
Female gametophyte
(embryo sac)
Antipodal cells
Central cell
Synergids
Egg (n)
Pollen
tube
Pollen
tube
Stigma
Sperm
(n)
Discharged sperm nuclei (n)
FERTILIZATION
Egg
nucleus (n)
Style
Sperm
THE ANGIOSPERM LIFE CYCLE

56. MEIOSIS
Key
Microsporangium
Microsporocytes (2n)
Generative cell
Anther
Tube cell
Pollen
grains
Microspore
(n)
Male gametophyte
(in pollen grain)
(n)
Mature flower on
sporophyte plant
(2n)
Haploid (n)
Diploid (2n)
MEIOSIS
Ovule (2n)
Ovary
Megasporangium
(2n)
Megaspore
(n)
Female gametophyte
(embryo sac)
Antipodal cells
Central cell
Synergids
Egg (n)
Pollen
tube
Pollen
tube
Stigma
Sperm
(n)
Discharged sperm nuclei (n)
FERTILIZATION
Germinating
seed
Embryo (2n)
Endosperm (3n)
Seed coat (2n)
Seed
Nucleus of
developing
endosperm
(3n)
Zygote (2n)
Egg
nucleus (n)
Style
Sperm
THE ANGIOSPERM LIFE CYCLE

57. Angiosperm Diversity
Monocots (one cotyledon)
¼ of angiosperm species
Eudicots (“true” dicots)
More than 2/3 angiosperm
species
TWO MAIN GROUPS OF ANGIOSPERMS

60. HUMAN WELFARE
• No group of plants is more important to
human survival than seed plants
• Plants are key sources of food, fuel, wood
products, and medicine
• Our reliance on seed plants makes
preservation of plant diversity critical

61. PRODUCTS FROM SEED PLANTS
• Most of our food comes from angiosperms
• Six crops (wheat, rice, maize, potatoes, cassava, and
sweet potatoes) yield 80% of the calories consumed
by humans
• Modern crops are products of relatively recent
genetic change resulting from artificial selection
• Many seed plants provide wood
• Secondary compounds of seed plants are used in
medicines