Chapter 3
BOT3015L
Biology of Flowering Plants:
Reproduction
Flowers and Pollination
Presentation created by Danielle Sherdan
All photos from Raven et al. Biology of Plants except when otherwise noted
Today
• Introducing angiosperms, flower structure and function
• Pollination
• Evolutionary trends in floral structure
• Inflorescences
• Monocots and dicots
Flowers are distinguishing
characteristics of angiosperms
All fruits come from flowers
Angion=vessel
Sperma=seed
Angiosperms have seeds contained
in a vessel (developing ovary)
Cherry
Saguaro cactus
Apple
Cattleya orchid
Sunflowers
Flowers
What are the functions of flowers?
How are these functions important for the
survival of species?
Honeysuckle
Flower dissection
a guided tour
Notice the arrangement of the floral parts
Arrangements of floral organs
Primitive
Advanced
Carpels
Stamens
Petals
Sepals
Spiral arrangement of
floral organs.
Arrangement of floral organs
in whorls.
Flower dissection
a guided tour
What are the functions of these floral parts?
Note that the petals are inserted after the sepals
Alternation of
Generations
generalized plant
life cycle
In angiosperms,
gametophytes are borne
within the reproductive
structures of the flower; thus
flowers are important when
discussing evolution of
angiosperms
Flower dissection
What are the
functions of
the stamens?
Hint:
collectively, the
stamens are
termed the
androecium
(andro=male,
ecium=house).
We will discuss
the
microgametophyte
next week
a guided tour
stamen
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?
Flower dissection
Ovary, ovules
(within ovary),
style, and stigma
comprise the
carpel
(megasporophyll)
What are the
functions of the
carpel?
We will discuss
more about the
megagametophyte
next week
a guided tour
stamen
Alternation of
Generations
generalized plant
life cycle
Requires pollination
In angiosperms,
gametophytes are born within
the reproductive structures of
the flower; thus flowers are
important when discussing
evolution of angiosperms
Today
• Introducing angiosperms, flower structure and function
• Pollination
• Evolutionary trends in floral structure
• Inflorescences
• Monocots and dicots
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
Some plants make big investments in
attracting animal pollination vectors
Nectar
Notice the pollen on the
hummingbird’s forehead and the
stigma that touches it as he feeds
Some plants make big investments in
attracting animal pollination vectors
Pollen
Seat bee gathering pollen
from the stamens of a cactus
flower
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/pollenadapt.html. (5-25-105).
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
Plants that rely on wind make big
investments in pollen
Notice the
stigmas that
fan out to
easily catch
pollen
grass
birch
Pollination Biology movie
Today
• Introducing angiosperms, flower structure and function
• Pollination
• Evolutionary trends in floral structure
• Inflorescences
• Monocots and dicots
Evolutionary Trends in Floral Structure
1. Reduction in number of parts
Perfect and Imperfect flowers
From
Outlaw lecture
Evolutionary Trends in Floral Structure
1. Reduction in number of parts
2. Cyclic arrangement (vs. spiral)
3. Fusion of organs
Fusion of floral parts
Outlaw lecture notes
Angel trumpet has fused
petals that form a floral tube
Fusion of organs
Danielle Sherdan
NE Tallahassee, FL
Notice the stamens fused to the carpel
of this hibiscus flower
Fusion of floral parts
Superior and Inferior ovaries
Advanced
Primitive
Superior ovary
(primitive)—note
typical appearance
of order of insertion
of floral parts.
Superior, parts
still appear to
arise in normal
order.
Inferior, floral tube
fused to ovary wall,
making ovary appear
to arise below other
floral parts.
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
Placentation
Within each ovule,
Marginal
double
fertilization, a Seeds attached
Primitive
distinguishing
to margin of
single carpel
characteristic of
angiosperms,
produces the zygote
Fusion of carpels
and endosperm.
Parietal
The ovary develops
into the fruit, another
distinguishing
Axile
characteristic
Advanced of
angiosperms
Free central
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
Bilateral and Radial Symmetry
This orchid, an advanced
monocot, displays bilateral
symmetry
This wintergreen displays
radial symmetry, which is
primitive, but fused carpels,
which is advanced
Today
• Introducing angiosperms, flower structure and function
• Pollination
• Evolutionary trends in floral structure
• Inflorescences
• Monocots and dicots
Inflorescences
Groups of flowers in particular arrangements
Some examples
Lupine
Inflorescences
Groups of flowers in particular arrangements
What is a fitness advantage of having inflorescences?
What is a fitness disadvantage of having inflorescences?
Inflorescences
Groups of flowers in particular arrangements
Notice that these
composites display
many evolutionarily
advanced
characteristics
Today
• Introducing angiosperms, flower structure and function
• Pollination
• Evolutionary trends in floral structure
• Inflorescences
• Monocots and dicots
Monocots and Dicots
the two major groups of angiosperms
Monocots and dicots have several differentiating characteristics
Number of cotyledons
Leaf venation
Number of flower parts
Observe today
In your lab notebook,
create a table to
contrast these traits
in monocots and
dicots
Seed structure at maturity
Function of cotyledons
Root structure
Secondary growth in shoot
Arrangement of vascular bundles