Original Research
Water repellance
of leaves
Miyako Ishio, Tamami Katsu, Nanaka Horii
Meiwa High School, Nagoya, Japan. E-mail: [email protected]
DOI: 10.4103/0974-6102.107622
ABSTRACT
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.
Introduction
What is an Angle of Contact?
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.
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].
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.
Young Scientists Journal | 2013 | Issue 13 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 nonwater repellent, have angles of contact less than 80
degrees.
Lotus was the most water repellent and bamboo the
least from the plants tested.
Lotus
Taro
Hydrangea
Bamboo
Appearance
Small particles on Surface
Small Projections on Surface
Dotted with very small cells
Smooth and white spots
Angle of Contact (O)
157
154
78
64
41
Discussion
Summary
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.
This experiment has helped me to further understand
the effectiveness of the water repellence as we can
Figure 4: Surface of Hydrangea under a microscope
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]
Lotus
Bamboo
Figure 2: Finding the angle of contact of a water droplet on a leaf
Figure 3: Surface of lotus under a microscope
42 Taro
Hydrangea
Figure 5: Water repellence of (from left to right): Lotus, taro, bamboo,
hydrangea
Figure 6: The lotus effect [Available from: http://www.balconette.
co.uk/articles/self-cleaning-glasses.aspx]
Young Scientists Journal | 2013 | Issue 13
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.
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.
Young Scientists Journal | 2013 | Issue 13 43