Distribution Of Growth
A Lab Experiment
Growth in plants refers directly to an increase in size
and weight. Often it is thought of as a process, but it is
more accurately described as a system of subprocesses.
(Meyer, 409) Growth is not equally distributed throughout a
plant, rather there are only certain areas in the plant
that will do the growing. (Distribution of Growth packet)
These areas are called meristems. These meristems allow for
cell division and enlargement. (Meyer, 409) When conditions
are favorable for the meristem, new cells will be produced
as a result of repeated mitosis. These meristems are
actually tissues, capable of growth throughout the entire
life of the plant. This is known as the plant's primary
growth. (Software Toolwork's Encyclopedia)
As stated before, growth only occurs in the meristems of a
plant. This means that only a certain part of a root, stem,
and leaf containing a meristem will grow. In most cases,
only the tip of a root grows. This is called the
rootapical meristem, which is responsible for developing
an extensive root system required for continued growth of
the plant. (Software Toolwork's Encyclopedia) The growth of
the stem is credited to the cambium, its meristem. Aside
from allowing the stem to grow thicker and taller, the
cambium also maintains the xylem and phloem. Producing
these other areas of tissue in a plant is called secondary
growth. (Meyer, 419) The cells inside a leaf are usually
arranged in two layers. There is an upper layer that is
made up of large palisade cells, and the lower is made up
of spongy tissues.
There are many other factors that also affect a plant's
growth. Some of these factors include the climate, ph of
rainfall, gases, and competition with other plants.
(Fuller, 238) Any one of these factors can greatly
contribute to a plants growth, both negatively and
positively.
Methods and Materials
To begin this lab, bean plants had to be grown. Although
only six plants had to be grown, this soon became a
troublesome task. After realizing the plants would not
sprout in time, we decided to stamp several leaves from the
plants grown in the environmental class. We stamped these
leaves with the India ink, this divided each leaf into
equal areas. The length and width of each leaf was
recorded, along with the measurements of each of the
regions made by the stamp. These measurements were taken
every three days over a twelve day period.
Next on our list was the root. Six seeds were placed in a
petri dish with wet paper towels. After the roots sprouted,
they needed to be marked with India ink, too. This was a
very tedious task because of the small size of the roots.
After the initial marking, two days had passed and new
results were recorded. After this, averages were figured
out for the length of the first two lines on each seed.
Finally came the stem. Six plants were grown, and marked
with the India ink. Ten marks each 2mm apart were made.
Like the roots, they were checked two days later and then
averages were drawn up.
Results:
Leaves:
The leaves were measured by their length, width, and
distance between the lines made by the India ink. On the
first day, we recorded:
Length Width Distance
Leaf #1 5.1cm 3.0cm .5cm
Leaf#2 4.5cm 2.5cm .5cm
Leaf#3 5.4cm 2.8cm .5cm
Leaf#4 6.1cm 2.9cm .5cm
The third day:
Length Width Distance
Leaf #1 5.1cm 3.1cm .5cm
Leaf#2 4.5cm 2.6cm .5cm
Leaf#3 5.5cm 2.9cm .5cm
Leaf#4 6.1cm 2.9cm .5cm
The sixth day:
Length Width Distance
Leaf #1 5.2cm 3.1cm .5cm
Leaf#2 4.5cm 2.7cm .6cm
Leaf#3 5.7cm 3.0cm .6cm
Leaf#4 6.2cm 3.0cm .6cm
The ninth day:
Length Width Distance
Leaf #1 5.3cm 3.2cm .5cm
Leaf#2 4.6cm 2.8cm .6cm
Leaf#3 5.8cm 3.1cm .7cm
Leaf#4 6.2cm 3.1cm .6cm
The last day (12) :
Length Width Distance
Leaf #1 5.3cm 3.3cm .5cm
Leaf#2 4.7cm 2.9cm .6cm
Leaf#3 6.0cm 3.1cm .7cm
Leaf#4 6.3cm 3.1cm .6cm
Roots:
An average was taken for the first two lines of the roots,
each segment after that was measured individually. Our
results are as follows:
Root#1 Segment Measurement
1+2 avg. .4cm
3 .2cm
4 .2cm
5 .2cm
6 .1cm
7 .1cm
8 .1cm
9 .1cm
10 .1cm
Root#2 Segment Measurement
1+2 avg. .5cm
3 .2cm
4 .2cm
5 .2cm
6 .1cm
7 .1cm
8 .1cm
9 .1cm
10 .1cm
Root#3 Segment Measurement
1+2 avg. .3cm
3 .2cm
4 .1cm
5 .1cm
6 .1cm
7 .1cm
8 .1cm
9 .1cm
10 .1cm
Root#4 Segment Measurement
1+2 avg. .3cm
3 .2cm
4 .2cm
5 .1cm
6 .1cm
7 .1cm
8 .1cm
9 .1cm
10 .1cm
Root#5 Segment Measurement
1+2 avg. .4cm
3 .2cm
4 .2cm
5 .1cm
6 .1cm
7 .1cm
8 .1cm
9 .1cm
10 .1cm
Root#6 Segment Measurement
1+2 avg. .4cm
3 .2cm
4 .2cm
5 .2cm
6 .1cm
7 .1cm
8 .1cm
9 .1cm
10 .1cm
Stems:
An average was taken for the first two lines of the stems,
each segment after that was measured individually, just as
the roots were done. Our results are as follows:
Stem#1 Segment Measurement
1+2 avg. .7cm
3 .4cm
4 .3cm
5 .2cm
6 .2cm
7 .2cm
8 .2cm
9 .2cm
10 .2cm
Stem#2 Segment Measurement
1+2 avg. .8cm
3 .5cm
4 .3cm
5 .3cm
6 .2cm
7 .2cm
8 .2cm
9 .2cm
10 .2cm
Stem#3 Segment Measurement
1+2 avg. .7cm
3 .5cm
4 .5cm
5 .3cm
6 .2cm
7 .2cm
8 .2cm
9 .2cm
10 .2cm
Stem#4 Segment Measurement
1+2 avg. .6cm
3 .3cm
4 .3cm
5 .2cm
6 .2cm
7 .2cm
8 .2cm
9 .2cm
10 .2cm
Stem#5 Segment Measurement
1+2 avg. .9cm
3 .7cm
4 .4cm
5 .3cm
6 .2cm
7 .2cm
8 .2cm
9 .2cm
10 .2cm
Stem#6 Segment Measurement
1+2 avg. .7cm
3 .4cm
4 .4cm
5 .3cm
6 .3cm
7 .2cm
8 .2cm
9 .2cm
10 .2cm
Discussion:
The growth of the leaves was about what we had expected it
to be. It was tough to get the plants to grow, probably due
to the cold draft from the window. This began to slow us
down and we ran short on time. The plants that were grown
from the environmental classes had to be used.
Before Christmas vacation, seeds were placed in petri
dishes with wet paper towels. By the time we came back we
could tell that the seeds had sprouted, but had died from
lack of water. It was determined that we would quickly have
to perform this experiment at Mr. Kihm's private
laboratory. After these measurements were taken we could
see that we had guessed right in that the most growth would
occur at the tip of the roots.
For the stem measurements we had to grow our own again at
Kihm's Science Museum. It came to be determined that the
average measurement for the stems was 2.83cm. The stem
results were on target with what we expected.
Conclusion:
Right from the very beginning of this lab we were plagued
with problems. From plants not growing at all, to ones that
did but died. From our readings, we were able to determine
that most growth would take place in the roots, leaves, and
stems. The most notable facts that we learned were that
plants do not mature like animals do, they are continually
growing, and that only certain parts of these plants do the
growing.
Bibliography:
Foresman, Scott. Biology. Oakland, New Jersey: Scott
Foresman and Company, 1988.
Franck, Irene, and David Brownstone. The Green
Encyclopedia. New York: Prentice Hall General Reference,
1992.
Fuller, Harry J., and Zane B. Carothers. The Plant World.
New York: Holt, Rinehart and Winston, Inc. 1963.
McLaren, Rotundo. Heath Biology. New York: Heath
Publishing, 1987.
Meyer, Bernard S., and others. Introduction to Plant
Physiology. New York: D. Van Nostrand Company, 1973.
The Software Toolwork's Multimedia Encyclopedia. New York:
Grolier, Inc., 1997.
