Young Scientists Journal | 2013 | Issue 13 41

Original Research

Water repellance of leaves

ABSTRACT

Introduction

Water repellence is used for various things, such as an umbrella [Figure 1] or a frying pan, in our daily lives. There are some plants such as the Lotus[1] [Figure 2] that also have water repellence. In this experiment we studied the effect of water repellence in plants and why it occurred.

Experiment

We conducted the experiment using leaves from lotus and taros plants because these are said to be water repellent. We also observed the leaves of hydrangeas and bamboo which are considered to be non-water repellent.

We observed the surface of leaves with a microscope [Figures 3 and 4] and then dribbled water on the surface of leaves to investigate the angle of contact [Figure 5]. Finally, we compared the results of the experiments for the different leaves.

What is an Angle of Contact?

The angle of contact is the angle where a liquid interface meets a solid surface. The angle of contact is recorded and used to deduce the water repellence of the leaf [Figure 6].

Results

Our results showed that water repellant plants such as Taros and Lotus plants had angles of contact greater than 150 degrees.

Hydrangea and Bamboo however, which are non-water repellent, have angles of contact less than 80 degrees.

Lotus was the most water repellent and bamboo the least from the plants tested.

Appearance Angle of Contact (O)Lotus Small particles on Surface 157Taro Small Projections on Surface 154Hydrangea Dotted with very small cells 78Bamboo Smooth and white spots 64

Some plants have been found to have hydrophobic surfaces and the properties of these were studied. The angle of contact of water droplets was measured under a microscope and compared for different species of plants. It was concluded that perhaps it was an effective adaptation for the lotus plant to wash mud off its leaves to maximize light exposure for photosynthesis.

Miyako Ishio, Tamami Katsu, Nanaka HoriiMeiwa High School, Nagoya, Japan. E-mail: ishi-mya@fdb.so-net.ne.jp

DOI: 10.4103/0974-6102.107622

42 Young Scientists Journal | 2013 | Issue 13

Figure 1: Water repellence is useful for umbrellas. Teflon in this case is the water-repellent material [Available from: http://global.rakuten.com/en/store/maxshare/item/a06360_sale]

Figure 2: Finding the angle of contact of a water droplet on a leaf

Figure 6: The lotus effect [Available from: http://www.balconette.co.uk/articles/self-cleaning-glasses.aspx]Figure 3: Surface of lotus under a microscope

Figure 4: Surface of Hydrangea under a microscope

Discussion

The effect of water repellence on a leaf, such as a lotus, is called the “self-purification effect”, and repels not only water but dirty water as well. Lotuses can grow in the mud; however, their leaves have to photosynthesize. Perhaps, this water repellence is an adaptation so that mud is washed off a leaf to maximise the quantity of light available for photosynthesis.

Summary

This experiment has helped me to further understand the effectiveness of the water repellence as we can

Figure 5: Water repellence of (from left to right): Lotus, taro, bamboo, hydrangea

Lotus Taro

HydrangeaBamboo

Young Scientists Journal | 2013 | Issue 13 43

About the Authors

Miyako Ishio She likes reading books. Her favourite book is Harry Potter. She wants to read it in English some day. Her dream is to research on Japanese society and culture. She is most interested in religion in Japan and about Japan's relations with foreign countries. Therefore, she studies Japanese, society, and English a lot.

Nanaka Horii Her dream is to be a doctor and she wants to help children in developing countries. So she studies a lot, especially in Maths and English so that she can enter a university. She learned from this project that she should continue even if she felt as though she couldn't finish it. Therefore, she'll never give up and she believes that she will carry on until her dream comes true.

Tamami Katsu She is currently studying for her entrance exams in January and February at the start of 2013. She is studying many subjects including Maths, Chemistry, Social Studies and English. She hasn't yet decided what kind of work she will do, but she hopes that she will be able to work abroad and with people from different countries. She would also like to do something helpful. She likes to watch British or American movies because they are more interesting than Japanese ones. She often goes to the cinema several times a month. She also likes to listen to music, especially One Direction.

see its practical effect. This experiment could be taken further by experimenting on various leaves to understand their structure which could be used to create water repellent products.

Reference

1. Tsujii K. Superhydrophobic and Superhydrophilic. Yoneda publisher; 2009.