1. Lecture 7:
Plants and Fungi

2. Fungi
Not plants, not animals
Multicellular eukaryotes
Not closely related to either animals or
plants

3. Fungus
Made of hyphae, which are thin cell
filaments packed closely together
Mycelium is the main body of the
fungus- it penetrates whatever the
fungus is growing on
They can be HUGE in the soil and cover
giant areas

4. Mushrooms
The part we eat is a fruiting body- it is
the part that produces spores, one way in
which fungi reproduce

5. Fungi in the Ecosystem
Most are decomposers that break down
organic waste in the soil
Can also feed on live animals and
plants (ringworm, for example)
Fungi also occur in mutualistic
relationships: lichen, mycorrhizal fungi

6. Economic Benefits
Make cheese, beer, bread, wine, soy sauce
Use to make medicines
Of course we also just eat them
Can break down some pollutants with
organic sources

7. Fungal Diseases
Can damage crops- corn smut
Candida- yeast infections, oral thrush
Can damage heart and brain if untreated
Tinea- ringworm, athlete’s foot
Batrachochytrium dendrobatidis- chytrid
fungus in frogs
Histoplasma- from bird droppings

8. Plants
Multicellular, eukaryotic, photosynthetic
Challenge: live on land, avoid drying out
Plants evolved from algae ~500 mya
5 main groups of plants
Each associated with an evolutionary
event

9. The 5 groups
Mosses: No way to transport water, but can
avoid drying out if in a moist area
Lycophytes: Have a vascular system to
transport water
Ferns: Have large leaves, allows more
photosynthesis
Gymnosperms: Have seeds
Angiosperms: Have flowers

10. Plant reproduction
Alternation of
Generations
A plant has two
forms: one is diploid
and the other is
haploid

11. Plant Reproduction
Dominant generation: The one we
recognize as the plant itself.
In vascular plants, this is the
sporophyte - only this generation
evolved vascular tissue. The
gametophytes are typically microscopic
In nonvascular plants, this is the
gametophyte

12. Nonvascular plants
Also called bryophytes
No true roots, stems or leaves- these
would require vascularity
Liverworts and mosses

13. Vascular Plants
Have roots, stems, and leaves
Roots absorb water from the soil, send it
up the stem to the leaves
Leaves covered by waxy cuticle to prevent
dehydration, except for stomata- pores
that allow for gas exchange

14. Vascular Plants
Vascular tissue is a big advantage, plant can live
further away from water, can get water out of the
soil
Vascular tissue has two parts:
Xylem- brings water and minerals up from soil
Phloem- brings organic nutrients form one part
of plant to another
Lignin- found in cell walls and makes them
very strong

15. Lycophytes
Also sometimes called club moss
Probably the first plants to develop
vascular tissue
Leaves are very small and each have a
single vein with xylem and phloem
Do not produce seeds

16. Ferns
Have megaphylls- large leaves with branched veins
These provide larger surface area for
photosynthesis
Do not produce seeds
During the Carboniferous period, the ferns and
lycophytes were the size of trees
When they fell, they were covered by water and
did not decompose completely- they were slowly
compressed to form....COAL

17. Seed Plants
Most plentiful plants today
Seeds consist of embryo (sporophyte), seed coat,
and stored food
Coat allows seed to stay dormant until
conditions are favorable to growth- some seeds
can be dormant for decades
Seed plants produce male and female
gametophytes: pollen is male, ovule (seed origin)
is female

18. Gymnosperms
Ovules and seeds are exposed on a cone
scale
Conifers (pines, cypress, firs, etc) are the
most common gymnosperms today
Well adapted to dry conditions
Needlelike leaves resist dessication
Can live in very cold regions

19. Angiosperms
Flowering plants
240,000 living species
The flowers are really the sex organs of
the plant

20. Flower Anatomy
Stamen
Contains
pollen
Stigma is sticky;
accepts pollen
grains

21. Angiosperms
The flower produces a seed; it is enclosed
by fruit
In order to angiosperms to reproduce,
they must spread pollen and then seeds
around
Flowers help to do this

22. Adaptations of Angiosperms
Wind-pollenated flowers- small and dull
Insect or bird pollenated- usually colorful and
larger
Bee-pollenated have ultraviolet colors to lead bees to
pollen
Night- blooming flowers to attract nocturnal
animals
Fruits enhance seed spread because eaten by
animals and thus dispersed

23. Importance of Plants
Food source
Wood products
Pharmaceuticals
Plants produce O2
Plants carry out carbon and water cycles
Some can absorb toxic chemicals
Aesthetic value

24. Flowering Plant Anatomy
Shoot System: stem, leaves and flowers
Root System: the roots
Terminal Bud: at tip of main stem or
root where primary growth occurs
Grow in both directions this way

25. Flowering Plant Anatomy
Leaves
Usually primary place for
photosynthesis
Require sunlight, CO2, and water
Can be highly modified
Cactus spines, tendrils, flytraps

26. Flowering Plant Anatomy
Stems
Supports leaves, transport between
roots and leaves, produces new tissue
Some stems do other things: cactus,
etc.

27. Flowering Plant Anatomy
Roots:
Supports and anchors the plant
Absorbs water and minerals from the
soil
Different structures: root hairs,
taproots, etc.

28. Monocots and Eudicots
Two types of flowering plants
Named after number of cotyledons-
embryonic leaves, in the seed.
Monocots have one, eudicots have two
Many differences between the two types
Monocots: grass, corn, lilies, palms, wheat
Eudicots: dandelions, oak trees, potatos

29. Monocots Eudicots
One cotyledon Two cotyledons
Parallel leaf veins Net veined leaves
Vasc. bundles in stems are Vasc. bundles in stems are in
scattered a circle
Flower parts in 3’s Flower parts in 4’s or 5’s
Seed chambers in fruit in 3s Seed chambers in fruit in 4’s
or 5’s
Tap root system Fibrous root systsem

30. Plant Tissue
3 Specialized tissues:
Epidermal tissue- outer protective
covering “skin”
Ground tissue: Interior of a plant,
carries out functions
Vascular tissue: Transports water and
nutrients, provides support

31. Plant Tissue
Plants continue to grow their entire lives
because they have merisetm tissue:
embryonic tissue that divides and can
produce any of the three specialized
types

32. Epidermis
The outer layer
Outside that is exposed to air is covered by
waxy cuticle- minimizes water loss
Protects plant from pathogens
In leaves, contain stomata- openings for gas
exchange to occur
In trees, cork replaces epidermis to help form
bark

33. Ground Tissue
Most of the plant is ground tissue- 3 kinds of
cells:
Parenchyma: least specialized cells, found
everywhere
Collenchyma: give flexible support to plant-
strands in celery, for example
Sclerenchyma: have cell walls that contain
lignin, makes them strong- mostly dead cells
like in nut shells, cotton and flax fibers

34. Vascular Tissue
Two types, usually found together
Xylem: water and minerals from roots
to leaves
Phloem: sugar, etc. from leaves to roots
X up, P down!
In the stem and roots, and the veins of
leaves

35. More About Leaves
Flat part is blade, stem that attaches leaf
to rest of plant is the petiole
Simple leaves- undivided
Compound leaves- several leaflets make
up one leaf
Most of the time, the cells that carry out
photosynthesis are in the leaves

37. More About Stems
Nonwoody stems- Herbaceous plants
Have vascular bundles that contain
xylem and phloem
Monocot stems are less organized than
eudicot stems- see book

39. More About Stems
Woody stems, such as in trees, have secondary
growth that increases the girth of the plant
Phloem is in the bark, so removing the bark
prevents transport of nutrients
Wood is secondary xylem, that increases year by
year- the wood is what carries enough water to get
all the way up to the leaves on the tree
Can tell a tree’s age by looking at annual rings
in the trunk

41. More About Roots
Very nice list of root structure and
function in book on page 351, please
refer to that for next slide

42. Pericycle can start
development of
new root branches
Endodermis
regulates what
enters vascular
tissue

43. Roots and Nutrients
Plants (and therefore all animals too) rely
on bacteria in the soil to fix N
Have a symbiotic relationship- the
bacteria take N from the soil, the plant
provides food for the bacteria
Plants also rely on fungus: mycorrhizal
association, to increase water uptake and
break down nutrients for the plant

44. Water transport in plants
How does water get from roots to leaves
without a heart or other organ to push it?
Cohesion-tension model
See book; drawing on board
LOTS of water lost from plants through
transpiration

45. Transpiration
Reduces flooding
Returns water to the water cycle from the
soil
Why plants need more water as they
grow- they are losing it all the time

46. Movement in Phloem
Pressure-flow model
1. Plants make sugar
2. It is transported to phloem through active transport
3. As it accumulates in phloem, water follows due to
osmotic pressure
4. Starts flow
5. Tissues without sugar are a SINK- they take up
sugar