Close-up View of a
by Brian Johnston (Canada)
This article focuses on an adulterated chrysanthemum
cut flower. As can be seen above, the blooms are startling
because of their intense blue colour. Unfortunately, the
colour is fake, having been produced by placing the cut stem in
a very concentrated solution of blue dye. The colouring
agent is transported up the stem by the water conducting tubes
(xylem) to the leaves, and flowers. Since the water can
exit these structures by the process of transpiration, while the
dye cannot, plant tissues become darker and darker in colour
until the stem is removed from the dye solution. In some
flowers, like the one shown here, the tissue at the tips of the
petals absorbs the solution more poorly than the rest, and this
accounts for the two-toned colouration. The white colour
of the petal tips is evidence of the fact that the flowers were
originally white. This dying process does not work on
living plants, since the roots selectively absorb only the
nutrients necessary for plant growth.
One of the side effects of
this process is that the green leaves end up a very visually
unpleasant muddy-purple colour. For this reason, I removed
all of the leaves before photographing the stem of
Like many other members of the
aster family, this chrysanthemum has a composite bloom
consisting of both inner disk flowers, and outer ray
flowers. Here, the outer flowers are long and
tubular. This is called the “quilled form”. Notice
in the images that follow, that the central disk flowers are
much shorter in length. Those at the very centre of the
bloom have a yellow colour, and are unopened.
A closer view of the disk
flowers shows that each possesses five pointed lobes.
On the other hand, the quilled
ray flowers have a variety of top-ends. Some are simply
curled backwards, while others have spoon-shaped tips.
If one of the spoon-shaped
petals is examined under the microscope, its jigsaw puzzle
cellular structure is revealed. (Petals of the other
chrysanthemum plant examined this month show a similar cellular
Notice in the two images that
follow, the opening process of the short disk flowers.
If one of the disk flowers at
the centre of the disk is carefully removed from the bloom, and
examined under the microscope, the dying process can be seen
clearly. In this case, the dye has advanced only to the
base of the flower.
In an outer ray flower, the
dye has advanced almost to the tip. Notice that the
natural yellow stripe on the flower has turned green (yellow +
blue = green).
An unopened disk flower can be
seen below. Note the many pollen grains that adhere to its
The higher magnification
photomicrograph that follows shows pollen grains to be
irregularly shaped and translucent.
Pollen grains are more
prevalent on the inner-most disk flowers.
The disk flower shown below
has been dyed right to the tip. Note that the flower’s
five lobes are clearly visible.
Finally, here are the
remaining images of this altered chrysanthemum. (The
strangely coloured leaves can be seen in the second image.)
Although this dyed
chrysanthemum is undeniably spectacular, there is something
distinctly unreal about it! I much prefer the natural
colours of undyed flowers.
The macro-photographs were
taken with an eight megapixel Canon 20D DSLR equipped with a
Canon EF 100 mm f 2.8 Macro lens which focuses to 1:1. A
Canon 250D achromatic close-up lens was used to obtain higher
magnifications in several images.
The photomicrographs were
taken with a Leitz SM-Pol microscope (using a dark ground
condenser), and the Coolpix 4500.
A Flower Garden of
A complete graphical index of
all of my flower articles can be found here.
The Colourful World
of Chemical Crystals
A complete graphical index of
all of my crystal articles can be found here.
Microscopy UK or their contributors.
Published in the
February 2014 edition of Micscape.
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