Tropical Morphology How Plants Adapt Rain Forest The University of Georgia College of Agricultural and Environmental Sciences Leaf Structures Extreme Adaptation

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 describe 3 ways tropical plants conserve water, and 3 ways plants manage extreme light levels found in the tropics 2. Be able to describe why plants that live in a rainforest region might have to conserve water, or manage very high light levels.

Extremes in The Rainforest

Tough Places for Rainforest Plants 1. The top of the plant canopy in a rainforest: – Very high light – Frequent high winds – Very hot leading to rapid drying 2). Dry slopes: – As warm, moist air rises over mountains, it loses its moisture as rain. The side facing the air current becomes a rainforest. The other side of the mountain is very dry and become desert-like. Thus some desert- like conditions are often nearby rainforests.

Dealing With Tropical Winds Bananas have leaves that can tear in high wing with without affecting photosynthesis. Tearing reduces wind force on the entire plant preventing it from toppling in storms.

Palms Are Coastal Survivors Palms often grow in windy, coastal areas. Like bananas, they have specialized leaves that allow wind to pass through without exerting a big force against the plant. This is how palms survive hurricanes.

Waxy Cuticle

Water Conservation

Cuticle and Storage

Heat and Wind Many orchids live at the top of the rainforest canopy. It can be dry, very hot and windy in the tops of the rainforest trees.

High Light Avoidance Light colored leaves reflects light, and tiny hairs reduce wind passing over the leaflets and thus reduces drying effects of wind.

High Light Avoidance Vertical, ribbon leaves Vertical, waxy leaves Tiny, hair-like leaves

Modified Leaves The string –o-pearls plant has modified leaves that are curled up to form a ball. This greatly reduces evaporation effects by wind and exposure to the sun’s heat.

High Light, High Heat, Wind and Predation Protection Cacti must be experts at leaf modification as they store water, thus being a good food source for animals. Spines and needles reduce foraging, while waxy layers and vertical leaves reduce water loss.

Summary We have seen that there are three very distinct regions of land in Costa Rica. Plants in the rainforest areas adapt to high rainfall, plants on the dry side of the mountains adapt to hot dry conditions. These adaptations to dry, hot windy conditions include waxy cuticle, vertical facing leaves, leaves that store water, leaf designs that reduce wind force, and leaves that are so modified that they don’t look like leaves!

Assessment Opportunity Describe three ways plants in a rainforest region that is dry adapt to the hot, dry and windy tropical conditions. Find a map of Washington State. Can you determine the wet and dry regions of the state? Did mountains play a role? Now look at a map of Costa Rica. Are they similar? What’s different?

For Future Exploration /FifthGrade_PlantAdaptations.pdf /FifthGrade_PlantAdaptations.pdf