Tropical MorphologyHow Plants Adapt Rain Forest

The University of GeorgiaCollege of Agricultural and Environmental Sciences

LeafStructures

Light Management Strategies

About The Author

• Dr. Paul A. Thomas– Professor of Floriculture– Department of Horticulture– The University of Georgia– Extension Specialist – Really into Photography!

Learning Objectives

• 1. Be able to decribe the ways plants manage light within their own canopy zone to enhance their own survival in low light conditions within the rainforest

• 2. Describe what a typical rain forest tree canopy looks like in cross section, and explain why this is so.

Rain Forest Canopy

Maintains Leaves Only Where There Is Light

Rapid New Growth When Sunlight Is Present

Epiphytic Growth On Branches

Epiphytic Growth on Stems/Trunk

Light Capture StrategyRadial Distribution of Leaves

Leaflets that can raise up or go flat depending on light levels.

Overlapping radial leaves

Staggered Leaflets allow leaflets to turn toward the light

Stagger Leaves – Larger the

spaces, the more likely the plant grows near the

forest floor.

Allowing light to pass through otherwise large leaves is how Philodendron shares light with leaves lower down on its stem.

Perforated Leaves

More Off-Set Leaves

A great place to study tropical leaf morphology!

Summary

We have seen that there are many different ways plant leaves can adapt to the relative lack of light under the forest canopy, or to the hot, intense tropical sunlight at the canopy. Leaf staggering, or light-sharing is a common approach to forest floor plants and vines that must collect every scrap of light that makes it down to the forest floor.

Assessment Opportunity • Explain how leaf orientation can help increase or

decrease light being received by the plant.

• How does having leaflets with the ability to bend towards light help forest floor plants?

• Which do you think is a more successful strategy? Being an epiphyte or eventually growing up to being a tall canopy tree? What are the advantages and disadvantages of both strategies?

For Future Exploration

• http://reocities.com/RainForest/5798/levels.html

• http://en.wikipedia.org/wiki/Phyllotaxis