View
252
Download
7
Category
Tags:
Preview:
Citation preview
BOT3015LBiology of Flowering Plants:
ReproductionFlowers 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
• Introducing angiosperms, flower structure and function
• Pollination
• Evolutionary trends in floral structure
• Inflorescences
• Monocots and dicots
Saguaro cactus Apple
Cherry
Flowers are distinguishing characteristics of angiosperms
All fruits come from flowers
Sunflowers
Cattleya orchid
Angion=vesselSperma=seedAngiosperms have seeds contained in a vessel (developing ovary)
Flowers
What are the functions of flowers?
How are these functions important for the survival of species?
Honeysuckle
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 dissectiona guided tour
Notice the arrangement of the floral parts
Arrangements of floral organs
Spiral arrangement of floral organs.
Stamens
Sepals
Petals
Carpels
Arrangement of floral organs in whorls.
Primitive Advanced
Flower dissectiona guided tour
Note that the petals are inserted after the sepals
What are the functions of these floral parts?
Flower dissectiona guided tour
stamen
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
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 dissectiona guided tour
stamen
We will discuss more about the megagametophyte next week
Ovary, ovules (within ovary), style, and stigma comprise the carpel (megasporophyll)
What are the functions of the carpel?
Alternation of Generations
generalized plant life cycle
In angiosperms, gametophytes are born within the reproductive structures of the flower; thus flowers are important when discussing evolution of angiosperms
Requires pollination
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
Cypridium sp.
Koning, Ross E. 1994. Pollination Adaptations. Plant Physiology Information Website. http://koning.ecsu.ctstateu.edu/Plants_Human/pollenadapt.html. (5-25-105).
Drugs (Intoxication)
Some plants make big investments in attracting animal pollination vectors
Ophrys bécasse Charentephotonature-pvd.chez.tiscali.fr/ ophrys.htm
Prospect of Sex (pseudocopulation)
Ophrys speculum
Plants that rely on wind make big investments in pollen
grass birch
Notice the stigmas that fan out to easily catch pollen
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
FromOutlaw lecture
Evolutionary Trends in Floral Structure
1. Reduction in number of parts
3. Fusion of organs
2. Cyclic arrangement (vs. spiral)
Fusion of floral parts
Angel trumpet has fused petals that form a floral tube
Outlaw lecture notes
Fusion of organs
Notice the stamens fused to the carpel of this hibiscus flower
Danielle SherdanNE Tallahassee, FL
Fusion of floral partsSuperior and Inferior ovaries
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.
Ancestral Derived
Evolutionary Trends in Floral Structure
1. Reduction in number of parts
3. Fusion of organs
2. Cyclic arrangement (vs. spiral)
4. Away from marginal placentation
Placentation
Parietal
Axile
Free central
Primitive
Advanced
MarginalSeeds attached
to margin of single carpel
Fusion of carpels
The ovary develops into the fruit, another distinguishing characteristic of angiosperms
Within each ovule, double fertilization, a distinguishing characteristic of angiosperms, produces the zygote and endosperm.
Evolutionary Trends in Floral Structure
1. Reduction in number of parts
3. Fusion of organs
2. Cyclic arrangement (vs. spiral)
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 derived
Today
• Introducing angiosperms, flower structure and function
• Pollination
• Evolutionary trends in floral structure
• Inflorescences
• Monocots and dicots
InflorescencesGroups of flowers in particular arrangements
Lupine
Some examples
InflorescencesGroups of flowers in particular arrangements
What is a fitness advantage of having inflorescences?
What is a fitness disadvantage of having inflorescences?
InflorescencesGroups 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 Dicotsthe two major groups of angiosperms
Monocots and dicots have several differentiating characteristics
Number of cotyledons
Function of cotyledons
Seed structure at maturity
Number of flower parts
Root structure
Secondary growth in shoot
Arrangement of vascular bundles
Leaf venation
Observe today
In your lab notebook, create a table to contrast these traits in monocots and dicots
Recommended