Chapter 3 BOT3015L Biology of Flowering Plants: Reproduction Flowers and Pollination

1
Chapter 3BOT3015LBiology of Flowering Plants
ReproductionFlowers and Pollination
Presentation created by Danielle Sherdan All
photos from Raven et al. Biology of Plants except
when otherwise noted
2
Today

• Introducing angiosperms, flower structure and
  function
• Pollination
• Evolutionary trends in floral structure
• Inflorescences
• Monocots and dicots

• Introducing angiosperms, flower structure and
  function
• Pollination
• Evolutionary trends in floral structure
• Inflorescences
• Monocots and dicots

3
Flowers are distinguishing characteristics of
angiosperms
All fruits come from flowers
Cherry
Cattleya orchid
Apple
Sunflowers
4
Flowers
What are the functions of flowers?
How are these functions important for the
survival of species?
Honeysuckle
5
Flower dissectiona guided tour
6
Arrangements of floral organs
Primitive
Advanced
7
Flower dissectiona guided tour
What are the functions of these floral parts?
Note that the petals are inserted after the sepals
8
Alternation of Generationsgeneralized plant life
cycle
9
Flower dissectiona guided tour
What are the functions of the stamens?
Hint collectively, the stamens are termed the
androecium (andromale, eciumhouse).
We will discuss the microgametophyte next week
10
The stamens of most grasses (left) and the paper
birch (right) are easily blown by wind.
The flowers of most grasses do not have showy
petals, why?
11
Flower dissectiona guided tour
Ovary, ovules (within ovary), style, and stigma
comprise the carpel (megasporophyll)
stamen
What are the functions of the carpel?
We will discuss more about the megagametophyte
next week
12
Alternation of Generationsgeneralized plant life
cycle
In angiosperms, gametophytes are born within the
reproductive structures of the flower thus
flowers are important when discussing evolution
of angiosperms
13
Today

• Introducing angiosperms, flower structure and
  function
• Pollination
• Evolutionary trends in floral structure
• Inflorescences
• Monocots and dicots

14
Pollination
In angiosperms, movement of the microgametophyte
(pollen grain) to the megagametophyte in the
ovule of the carpel
How does a sessile organism, the microgametophyte
in the case of angiosperms move?
Vectors
In the following discussion, notice the
co-evolution of flowers and their biotic vectors
15
Some plants make big investments in attracting
animal pollination vectors
Nectar
Notice the pollen on the hummingbirds forehead
and the stigma that touches it as he feeds
16
Some plants make big investments in attracting
animal pollination vectors
Pollen
Seat bee gathering pollen from the stamens of a
cactus flower
17
Some plants make big investments in attracting
animal pollination vectors
Drugs (Intoxication)
Cypridium sp.
Koning, Ross E. 1994. Pollination Adaptations.
Plant Physiology Information Website.
http//koning.ecsu.ctstateu.edu/Plants_Human/poll
enadapt.html. (5-25-105).
18
Some plants make big investments in attracting
animal pollination vectors
Prospect of Sex (pseudocopulation)
photonature-pvd.chez.tiscali.fr/ ophrys.htm
Ophrys bécasse Charente
Ophrys speculum
19
Plants that rely on wind make big investments in
pollen
Notice the stigmas that fan out to easily catch
pollen
birch
grass
20
Pollination Biology movie
21
Today

• Introducing angiosperms, flower structure and
  function
• Pollination
• Evolutionary trends in floral structure
• Inflorescences
• Monocots and dicots

22
Evolutionary Trends in Floral Structure
1. Reduction in number of parts
23
Perfect and Imperfect flowers
From Outlaw lecture
24
Evolutionary Trends in Floral Structure

1. Reduction in number of parts

2. Cyclic arrangement (vs. spiral)
3. Fusion of organs
25
Fusion of floral parts
Outlaw lecture notes
Angel trumpet has fused petals that form a floral
tube
26
Fusion of organs
Danielle Sherdan NE Tallahassee, FL
Notice the stamens fused to the carpel of this
hibiscus flower
27
Fusion of floral partsSuperior and Inferior
ovaries
Advanced
Primitive
Superior ovary (primitive)note typical
appearance of order of insertion of floral parts.
Inferior, floral tube fused to ovary wall, making
ovary appear to arise below other floral parts.
Superior, parts still appear to arise in normal
order.
28
Evolutionary Trends in Floral Structure

1. Reduction in number of parts

2. Cyclic arrangement (vs. spiral)
3. Fusion of organs
4. Away from marginal placentation
29
Placentation
Within each ovule, double fertilization, a
distinguishing characteristic of angiosperms,
produces the zygote and endosperm.
Marginal Seeds attached to margin of single carpel
Fusion of carpels
Parietal
The ovary develops into the fruit, another
distinguishing characteristic of angiosperms
Axile
Free central
30
Evolutionary Trends in Floral Structure

1. Reduction in number of parts

2. Cyclic arrangement (vs. spiral)
3. Fusion of organs
4. Away from marginal placentation
5. Away from regularity e.g. toward
bilateral symmetry over radial symmetry
31
Bilateral and Radial Symmetry
This wintergreen displays radial symmetry, which
is primitive, but fused carpels, which is advanced
This orchid, an advanced monocot, displays
bilateral symmetry
32
Today

• Introducing angiosperms, flower structure and
  function
• Pollination
• Evolutionary trends in floral structure
• Inflorescences
• Monocots and dicots

33
Inflorescences
Groups of flowers in particular arrangements
Some examples
Lupine
34
Inflorescences
Groups of flowers in particular arrangements
What is a fitness advantage of having
inflorescences?
What is a fitness disadvantage of having
inflorescences?
35
Inflorescences
Groups of flowers in particular arrangements
Notice that these composites display many
evolutionarily advanced characteristics
36
Today

• Introducing angiosperms, flower structure and
  function
• Pollination
• Evolutionary trends in floral structure
• Inflorescences
• Monocots and dicots

37
Monocots and Dicotsthe two major groups of
angiosperms
Monocots and dicots have several differentiating
characteristics
Number of cotyledons
Leaf venation
Number of flower parts
Seed structure at maturity
In your lab notebook, create a table to contrast
these traits in monocots and dicots
Function of cotyledons
Root structure
Secondary growth in shoot
Arrangement of vascular bundles