Close-up View of Two
Tulipa x hybrida
by Brian Johnston (Canada)
The flamboyant flowers discussed in the
two articles this month are certainly different than the normal
garden-variety tulips found in most spring gardens. What makes
them so special to a macro-photographer, is their continued visual
interest as one moves up the magnification scale. Each bud can be
considered to be a colourful sculpture, with striking structure that
continues to interest the observer as he or she moves closer.
Although tulips are often associated with the Netherlands, they are not
a native Dutch flower! About four hundred years ago Europeans
first discovered tulips in Turkey. At that time Carolus Clusius,
a famous botanist, introduced the plant to the Leiden botanical gardens
in Holland. Since tulips were extremely rare, and expensive, only
Kings and Emperors could afford to plant them in their gardens.
The immediate popularity of the tulip drove Clusius and other
horticulturalists to produce new colour variations to satisfy the
growing demand for the flowers. Over the years, many tulip forms
were produced by crossing and hybridizing techniques. Some had
frilly petals, and dramatic flame-like colourations, that later became
known as “Parrot tulips”. In the 20th century, these
distinctive characteristics were found to be the symptoms of the mosaic virus which was transported
to the tulip plant by a louse living on peaches and potatoes!
Today, hybrids have been developed with similar visual characteristics,
but without the virus infection.
In your mind, compare normal tulips, with their single-coloured, solid,
smooth petals, with the parrot variety that can be seen above, and in
the two images that follow. Parrot tulips are characterized by
petals that are curled and twisted. They also have borders that
are fringed (laciniate).
Both varieties share the same characteristic lance-shaped (lanceolate), bright green leaves.
Notice the interesting, rather random colouring of individual petals in
the two images below. The colour ranges from bright red, through
yellow, to almost black!
Petals have an irregular, three-dimensional fringe along their upper
edge, as well as occasional projections of various sizes that emanate
from their outer edges.
Viewed from behind, the smooth green stem supports the base of the
flower. In fact, the stem is the weak point of many parrot tulip
varieties, as it is often too weak to support the fully open
flower. For this reason, many parrot tulips are suitable only as
Just how flamboyant the blooms are, can be seen below. Notice
that unlike normal tulip petals, each parrot tulip petal has its own
individual characteristics. Rotating a bloom shows a different
structure with each viewpoint.
Each flower has six petals arranged with three in an inner circle, and
three in an outer circle. As a flower begins to open, the outer
three petals move away first.
As we move closer to the petals of a flower, the sculptural nature of
the surfaces becomes more evident.
Closer still, the petals resemble the wildest imaginings of a
hallucinating modern sculptor!
If a section of one of the petals is examined under the microscope
using increasing magnification, its cellular structure eventually
Right at the upper edge of a petal, an unusual histogram-like pattern
can be observed.
When a flower opens sufficiently, its reproductive structures become
To get a clearer view, I have removed all but two of the petals.
Protruding from the top of the stalk is the white pistil, topped by the
stigma. Surrounding the pistil is a ring of six stamens.
Two closer views reveal more details. The stigma is tri-lobed,
and is connected without a stalk to the light greenish-white
ovary. A stigma without a stalk (or style) is referred to as sessile. The six pollen
covered anthers are supported by rod-like filaments.
Notice in the more highly magnified view of an anther shown below, that
it is composed of four parallel segments. Tulip pollen is dark in
colour and can be seen clearly if it gets on hands or light-coloured
clothing. (The dark out-of-focus spots that can be seen on the
yellow base of the petal at left are actually clumps of this dark
When examined under the microscope, the cellular structure of one of
the supporting filaments is colourful!
Several clumps of irregularly shaped pollen grains can be seen clinging
to a filament in the two images that follow.
Several anthers in the flower appeared to have this strange folded
shape at their bases. At this magnification it is almost possible
to see individual pollen grains on the anther’s surface.
By sliding the dark-ground condenser slightly out of the optical path,
it is possible to show the pollen grains adhering to the edge of an
anther. In this light, they appear to have a purple colour.
This same purple colouration also appears in a higher magnification
phase-contrast view of a single pollen grain.
The three images below show the top of the tri-lobed stigma. Each
lobe appears to have a deep groove in its upper surface, no doubt to
increase its surface area (and therefore its pollen collecting
capability). Dark pollen grains can be seen clinging to the
stigma’s surface in all three images.
Photomicrographs showing the surface of the stigma can be seen
below. Note the hair-like protuberances that cover the
surface. Pollen grains, carried to the stigma by visiting
insects, are caught by these hairs.
“Botanical tulips” like the
parrot tulips studied in this article, are marvels of what modern
biological science can produce. How strange it is to consider
that a louse carried virus produced such stunningly colourful
blooms. How wonderful that science could retain the striking
characteristics, while removing the disease!
In part two of this article (below), a different parrot tulip, with
even stranger sculptural qualities, is examined macro-photographically.
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
dark ground and phase-contrast condensers), and the Coolpix 4500.
The history of the Tulip
How did a flower cause an economic
Microscopy UK or their contributors.
Published in the
December 2006 edition of Micscape.
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