Pollination Systems and Reproductive Biology
Pollination is the transfer of pollen grains from an anther to a stigma
It is required for sexual reproduction but not for asexual reproduction
Flowers are the focal point for delivery and receipt of pollen
Self-pollination vs. Outcrossing
Self-pollination is when pollen from a plant is transferred to a stigma of the same plant, either within a flower or between flowers.
Outcrossing is when pollen from one plant is transferred to the stigma of another
Pollination Syndromes are lists of features that are associated with a particular mode of pollination
Self Pollination Syndrome
Small, inconspicuous flowers
Usually unpigmented (green or white flowers)
Low pollen: ovule ratio
Anthers positioned close to stigmas
Small pollen grains
Wind Pollination Syndrome
Be small and inconspicuous
Have large amounts of tiny pollen grains
Have large feathery stigmas
Water Pollination Syndrome
Water pollinated flowers tend to:
Be small and inconspicuous (and submerged or floating)
Have lots of small pollen grains (sometimes floating)
Have large feathery stigmas (sometimes floating)
All forms of animal pollinators
Rewards vs Attractants
REWARDS: Rewards are the things that animal pollinators visit flowers for.
ATTRACTANTS: Attractants are the cues that animals use to locate flowers.
Bee-pollinated flowers tend to fall into two classes:
Showy, open, bowl-shaped flowers that are relatively unspecialized
Showy, complicated, zygomorphic flowers that are more specialized
All be flowers tend to be yellow or blue, often with UV nectar guides and scented
Butterfly-pollinated flowers tend to:
be large and showy
be pink or lavender
have long narrow corolla tubes
Moth-pollinated flowers tend to:
be large and showy
have tubular corollas
have a sweet scent produced in the evening
Fly-pollinated flowers tend to:
have a strong unpleasant odor
be brown or orange in color
Bird-pollinated flowers tend to be:
large and showy
produce a lot of nectar
they usually lack a scent
Bat -pollinated flowers tend to:
be large and showy
be white or light-colored
have a strong scent of cabbage or fermented fruit
open at night
A pollination system, usually found in orchids, where a flower resembles a female wasp, and the male wasp lands on the flower to try to copulate, fails, and makes the same mistake again.
The study of plant reproductive methods such as phenology, breeding systems, pollination, floral structure, and dispersal.
The inability of a bisexual plant (hermaphrodite) to produce zygotes from its own pollen.
Gametophytic--mating opportunities determined by the genotype of the pollen
Sporophytic--mating opportunities determined by the genotype of the sporophytes (pollen and egg parents).
The timing of events, particularly in reference to reproductive events.
Any scale from hourly, daily, or annual.
Systems of sexuality in flowering plants which impact the relative rates of inbreeding or outcrossing.
The simplest and most common breeding system is hermaphroditism, where each plant has both female and male functions and all flowers are perfect.
Dioecy is the second most common breeding system found in plants; individuals are either female or male and have either staminate or pistillate flowers.
Monoecy is the another common breeding system found in plants; individuals are hermaphroditic but lack perfect flowers, instead having both staminate or pistillate flowers.
The breeding system in which there are two types of plants, females (with pistillate flowers) and hermaphrodites (with perfect flowers).
The breeding system in which there is a single type of plant, but with two types of flowers, pistillate and hermaphroditic.
The breeding system in which there are two types of plants, males (with staminate flowers) and hermaphrodites (with perfect flowers).
The breeding system in which there is a single type of plant, but with two types of flowers, staminate and hermaphroditic.
Evolution of Breeding Systems
Hermaphroditism and dioecy are stable systems, the other breeding systems are sometimes thought to be transitory between them.
Generally breeding system evolution is thought to be triggered by inbreeding and inbreeding depression, but resource allocation may also play a role.
Movement of plants from place to place, usually in the form of seeds, but sometimes also in the form of pollen.
Dispersal is the mechanism through which gene flow occurs.
Abiotic elements: wind, water, gravity.
Biotic elements: animals (by eating, sticking to surface, pollination) or by self dispersal (explosive fruits).