Wang_teacher_resource_pollination.pdf

8/13/2019 Wang_teacher_resource_pollination.pdf

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Flower Adaptations for Pollination

A Teacher Resource GuideCompiled by Diane Wang

[email protected]

What Is Pollination?

The process seeded plants (angiosperms

and gymnosperms) use to transfer their

male gametes to their female gametesleading to fertilization and the production

of new seeds. We will focus on flowering

plants, the angiosperms!

The male gametes (sperm) are contained

in pollen grains. The male reproductive

organs (filament and anther) are

collectively called the stamen. Pollen grains are produced in anther sacs.

Female gametes (eggs) are contained

within the ovary. The female reproductive

organs (stigma, style, and ovary) are

collectively called the carpel.

Figure below: structure of typical flower

from http://www.kidsgardening.com/onlinecourse/Diagram

s/new/c7-1flower.gif

Types and Mechanisms of Pollination

Plants can be outcrossing (cross-pollination among different plant individuals), inbreeding (self-

pollination), or both. This guide will focus on mechanisms of cross-pollination which maintains

genetic diversity within populations.

Pollination may occur with the help of wind, water, or animals.

http://www.kidsgardening.com/onlinecourse/Diagrams/new/c7-1flower.gif









Wind-Pollinated Plants

Do not produce scented flowers or nectar.

Flowers are small and inconspicuous, so no bright colors.

Flowers are often arranged in inflorescences (many flowers grouped together).

Large feathery stigma to catch pollen.

Many trees and grasses are wind-pollinated. Need to produce large quantities of pollen (this is what causes “hay fever” in the summer).

Water-Pollinated Plants

Rare.

Plants release pollen into the water which is carried by currents to other plant individuals. Occurs in

Posidonia australis (an Australian seagrass).

Pollen can also float on top of water. This type of pollination occurs in Potamogeton (pondweed).

Animal-Pollinated Plants: Structural Adaptations

Bees: flowers have landing platforms.

Hummingbirds: Hanging flowers work well as hummingbirds are master hoverers and do not need to

land.

Strategic placement of anthers and stigma on flower to hit the insect/bird in ideal position for

maximum pollen transfer as the pollinator moves between plants. Moths: long nectar tube suited just for moths’ long tongues.

Animal-Pollinated Plants: Visual Adaptations (Color and Pattern)

Bees: flowers have nectar guides to help guide diurnal (active during the daytime) insects to location

of the nectar in the flower. Most of the nectar guides are in ultraviolet wavelengths (UV) seen by

most insects. UV is out of the range of human vision (we see red, orange, yellow, blue, indigo, and

violet). Violet is the highest energy wavelength we see, and is close to ultraviolet. Hummingbirds: these birds prefer red flowers, hence many hummingbird feeders are red colored.

Moths: usually white or pale flowers because they provide the most visual contrast with background

vegetation for night flying moths.



Animal-Pollinated Plants: Olfactory Adaptations

Moths: flowers usually strong and sweet smelling flowers to attract the insects during the night.

These smells are appealing to humans, like Gardenia. Interesting fact: The perfume Chanel No. 5

is based off of the scent from Ylang Ylang, a moth-pollinated flower!

Flies and beetles: carrion flowers attract these insects using mimicry smells (dung or rotting flesh

scents). Not appealing to humans!



Pollination Syndrome Table from the U.S. Forest Servicehttp://www.fs.fed.us/wildflowers/pollinators/syndromes.shtml

Bats Bees Beetles Birds Butterflies Flies Moths

Color Dull white,

green orpurple

Bright

white, yellow,

blue, or

UV

Dull white

or green

Scarlet,

orange, redor white

Bright,

including redand purple

Pale and

dull to darkbrown or

purple;

flecked

with

translucent

patches

Pale and

dull red,purple,

pink or

white

Nectar

Guide

Absent Present Absent Absent Present Absent Absent

Odor Strong

musty;

emitted at

night

Fresh, mild,

pleasant

None to

strongly

fruity or

fetid

None Faint but

fresh

Putrid Strong

sweet;

emitted at

night

Nectar Abundant;

somewhat

hidden

Usually

present

Sometimes

present;

not hidden

Ample;

deeply

hidden

Ample;

deeply

hidden

Usually

absent

Ample;

deeply

hidden

Pollen Ample Limited;

often sticky

and

scented

Ample Modest Limited Modest in

amount

Limited

Flower

Shape

Regular;

bowl

shaped –closed

during day

Shallow;

have

landingplatform;

tubular

Large

bowl-like,

Magnolia

Large

funnel like;

cups,strong

perch

support

Narrow tube

with spur;

wide landingpad

Shallow;

funnel like

or complexand trap-

like

Regular;

tubular

without alip



Additional Resources

Websiteshttp://www.botany.uwc.ac.za/ecotree/flowers/pollination3.htm

A fine summary of the different mechanisms of pollination. Groups them into wind, water,

insects, mammals, and birds. I would say this is a great site to start with.

http://biology.clc.uc.edu/courses/bio303/coevolution.htm

This website focuses on the co-evolution aspect of pollination. This is a great resource

when doing a unit on evolution because it provides specific examples of plant-pollinator pairs

which show definite dependence on each other. The site has great pictures to use for

printing out or perhaps putting on a powerpoint to show students.

http://www.cas.vanderbilt.edu/bioimages/pages/pollination.htm

If you want to talk specifically about pollination syndromes, this is the place to go. It has got

great links to specific examples of each pollination syndrome and links to a series of pictures

for each angiosperm with close-ups of different parts of the plant, not just the flower. I used

this site for a lot of my pictures of carrion flowers. Good quality photos.

http://www.biologie.uni-hamburg.de/b-online/library/snapdragon/snapdragon_pollination.html

The snapdragon is the classic example of a plant with structural adaptation for its pollinator

(bees!). This site is all about snapdragon pollination. It has a good collection of pictures

that show how the snapdragon discriminates which insects get to get its nectar and which

ones do not, which is really cool. The snapdragon is certainly one picky plant!

http://waynesword.palomar.edu/ww0602.htm carrion

This site is devoted to some very stinky flowers. Great pictures and scientific names listed

with every example the site gives (if your students are into knowing big words). I found this

absolutely fascinating and could not believe some of these plants even exist! Just looking at

http://www.botany.uwc.ac.za/ecotree/flowers/pollination3.htm



http://www.biologie.uni-hamburg.de/b-

http://www.biologie.uni-hamburg.de/b-



http://www.botany.uwc.ac.za/ecotree/flowers/pollination3.htm



the pictures of these extremely weird flowers will make you appreciate the immense diversity

among angiosperms. I think students would love learning about flowers that smell atrocious.

BookWaser, Nickolas M. and Ollerton, Jeff. Plant Pollinator Interactions: From Sp ecialization to

Generalization. Chicago: University of Chicago Press, 2006.

Lengthy reference for more in-depth information on pollination ecology. Very detailed,

probably suited for teaching the middle school or older group.

Documents

Wang_teacher_resource_pollination.pdf