Biology, 6e

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LEC 09
Grasses Part I
FIELD BOTANY Lecture 09 Dr. Donald P. Althoff
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gymnosperms
DICOTS
Flowers
MAGNOLIOPHYTA
Seed-bearing
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Plantae
Magnoliophyta (Anthrophyta)
Liliopsida-moncots
Kingdom Division Class ORDERS- F
AMILIES-
Cyperales
Juncales

Cyperaceae
Juncaceae
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2
3
grasses
sedges
rushes
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Grasses ______ diverse

• Grasses 600 genera between
  ______________ species
• Sedges 70 genera 4,000 species
• Rushes 8 genera 400 species

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Grasslands of the world
Tropic of Cancer
EQUATOR
Tropic of Capricorn
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Historically, prairie covered 400,000 mi2 of
North America
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____
C3 plantsall of carbon fixation
and photosynthesis happens in _______________ just
on the surface of the leaf. C3 plants include
most temperate plants (except many grasses)more
than _____ of all earths plants.
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____
C4 plantscarbon fixation and photosynthesis
split between the ________________________________
_____. Warm season grasses? _________ plant
group in the short, mixed, and tallgrass
prairies
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Stomata, CO2, Fixation

• C3 plants--uses the enzyme rubisco to fix carbon
  dioxide to RuBPafter fixation is PGAL, a
  _________________
• C4 plants--do not directly use Calvin cycle and
  produce immediately a _________________
• ____ plants--uses PEP carboxsylase to fix CO2 at
  night (example cacti)

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CAM Plants

• ____________________________
• Fixation of CO2 at night, stored in the form of
  malate in large vacuoles in the mesophyll cells
  is available the next day.
• Stomata remained ______ during the day!!!

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CO2
H2O
Calvin cycle
O2
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? 3 carbon molecule
Calvin cycle
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• 4 carbon molecule
• before Calvin cycle

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Night

• 4 carbon molecule
• before Calvin cycle that is
• banked at night

• Calvin cycle completed during the day

Day
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Leaf Structure for ___ and ___ plants
____________cells
stoma
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Leaf Structure

• C3 bundle sheath cells lack chloroplasts
• C4 bundle sheath cells __________________
• CAM _____________ in mesophyll cells

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Enzyme utilized

• C3 rubisco
• C4 pepco
• CAM pepco

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Optimum Temperature

• C3 15 25 C __________
• C4 30 40 C __________
• CAM 35 C __________

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Approximate optimum (dark shades) and range
(light shades) when C3, C4, and CAM plants start
to grow/conduct photosynthesis efficiently
40
104
30-40oC 86-100oF
35oC
35
95
30
86
25
77
15-25oC 60-77oF
oC
oF
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68
15
59
10
50
5
41
0
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C3 Cool season
C4 Warm season
CAM
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What do we mean cool vs. warm season?

• Peak period of plant productivityand flowering

F
F
F
F
F
F
F
F
F
F
Growing season
cool
cool
warm
J F M A M J J A
S O N D
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Productivity rate(tons/hectare/year)

• C3 22 /- 0.3
• C4 39 /- 17
• CAM low variable

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C3 Plants - examples

• Peas
• Spinach
• Broccoli
• Kentucky bluegrass
• Tall fescue

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C4 Plants - examples

• Corn
• Soybeans
• Tomatoes
• Indiangrass
• Buffalo grass
• Big bluestem
• Blue grama

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Adaptation to the Environment

• These 3 different ways (i.e., C3, C4, and
  CAM)to accomplish photosynthesis illustrate how
  organisms _________________ to their environment.
  Each has its advantages and disadvantages
• C4 likely _______ in high light intensity, high
  temperature, and limited rainfall environments.
• C3 likely _______ in lower light intensity,
  moderate temperature, and more abundant rainfall
  environments
• CAM likely _______ in extremely arid
  environments
• (ferns and cone-bearing plants exhibit
  this process in addition to many flowering
  plants like some orchids and lily species)

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Characteristics to note for GRASSES

• Inflorescences
• Spike vs. spikelets
• Ligule design (see _____________ set)
• Floret composition (palea, lemma, awns)
• Seed heads (panicle vs. spike)
• Fruits (are grains compared to rushes and
  sedges)

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_______________ arrangement of flowers on the
stem
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Spike vs. ________
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Seed heads_______ vs. _______
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SPIKELET
seed
palea
lemma
FLORET
awn
30
awn
lemma
SPIKELET
palea
FLORET