Urban Ecology

Desert Plants

What it does

This experiment shows you how different leaf structures lose water at different rates.

What you need

Three paper towel sheets
A sheet of waxed paper
A large baking sheet
Two paper clips

What to do

Moisten each of the paper towels with water so that they are damp all the way through, but not dripping.
Lay one paper towel flat on the baking sheet.
Roll up one paper towel and place it on the baking sheet.
Roll up the last paper towel and cover the outside with waxed paper.
Secure the waxed paper to the towel at each end with the paper clips, then place it next to the others on the baking sheet.
Place the pan somewhere indoors where it will receive direct sunlight, then let it sit for 24 hours.
After 24 hours, unroll the paper and feel it.

What it's all about

The flat towel will be dry. The rolled towel will be mostly dry with some damp spots. The towel covered with waxed paper will be damp all over. Water evaporates faster when more surface area is exposed to the air. Plants that live in wet climates often have broad, flat leaves. In the desert, plants often have thick, round leaves that expose less surface area, helping them hold onto their water. In addition, many desert plants have a waxy coating on their leaves, like the waxed paper. This helps them hold in even more water in a very dry environment.

Remember, be sure you have a parent, teacher, or other adult help you!