Close-up View of a "Moth Orchid" Hybrid
(Phalaenopsis Luchia Lady x New Glad)
by Brian Johnston (Canada)
Southern Ontario winter is not conducive
to the collection and photography of wildflowers. As I write this
article, the outside temperature hovers at -25 degrees Celsius and the
landscape is covered by a thick layer of snow. Fortunately,
modern horticulture and transportation services provide us with the
tropical blooms of warmer climes at any time of year. The subject
the article was purchased from a large building supply store during a
trip to obtain light bulbs. I had been looking for an attractive,
healthy orchid for several weeks in garden centres, but strangely, this
was the best that I had seen.
The flower of a phalaenopsis orchid
resembles a moth in flight, and thus it is understandable that the
common name for the plant is “Moth Orchid”. Phalaenopsis originates from the
Greek phalaina, meaning
“moth” and opsis, meaning
“like”. The original phalaenopsis orchids were difficult to grow
in the home environment and over the years, intensive
cross-fertilization has produced a large number of colourful hybrids that thrive in this
environment. According to the information supplied with my
plant, two phalaenopsis hybrids, New
Glad and Luchia Lady
were crossed to produce white flowers with striking red veins and spots.
Although my specimen was grown in a
greenhouse in the United States (Florida) and transported to Canada,
phalaenopsis orchids are native throughout Southeast Asia, and can be
found from the Himalayan mountains to as far south as the Philippines
and northern Australia. They tend to grow in the shade below the
canopies of moist and humid lowland forests. Most plants have
four or five fleshy, dark green leaves. These leaves can be seen
in the image below, taken immediately after the orchid was purchased.
As regular readers of my wildflower
articles know, I favour a black, rather than natural background for my
images, since it increases the contrast and seems to show details more
clearly. For comparison, images using both techniques are shown
The closer views of a flower in the
following images reveal several of the unique characteristics of the
orchid family. Blooms consist of three petals and three
petal-like sepals (modified
leaves). At an early stage, these three sepals form the
protective sheath of the unopened bud. In addition, one of the
petals is special, being particularly colourful and projecting out
towards the viewer. This is called the lip or labellum of the bloom. The
positions of the various flower parts are shown in the third , labelled
image. It is interesting that as the flower begins to bloom, its
stem twists in order that the lip or labellum is positioned at the
bottom of the flower when it finally opens. (This process is
From behind, the three sepals are
clearly visible. Note how similar their colouration is to the
actual petals. By contrast, in most wildflowers, the sepals look
more like leaves, and are usually green.
The buds and flowers grow in
alternating fashion on both sides of the stem. (The image is
taken from below, looking up at the bottom of the flowers.) The
brown plant stem tends to be rather tough and woody, whereas the
pinkish flower stems are fleshy and more fragile.
The side views below of a
phalaenopsis flower show the projecting petal or lip. In
resupinate orchids, this more colourful petal helps to attract insect
visitors and provides a landing platform when they arrive. This
particular species possesses two hook-like appendages on the lip that
curve back towards the centre of the bloom.
The labelled image below shows the
main parts of the phalaenopsis’ reproductive system. At the
centre of the flower is a roughly cylindrical projection called the column. This is actually a
continuation of the stem of the flower. This column, (sometimes
called the gynandrium),
contains the male stamens and female pistil. Covering the end of
the column is the anther cap
which will be discussed later. For fertilization to take place,
an insect must alight onto the lip, climb into the throat and up onto
the strangely shaped, red-spotted yellow platform beneath the column.
A closer view reveals that the
insect is funnelled into the correct position by the walls formed by
two of the three lobes of the “lip” petal. Note that the end of
the column looks remarkably like the head of a bird with its
downward-pointing “beak”, and two red-edged “eyes”. The
“platform” for insects investigating the flower is located conveniently
immediately beneath the column.
The two images below show the
column viewed from above, and slightly below. In the second
image, if you look closely, two round yellow structures are visible
beneath the pale white membrane, (the anther cap). These are the
two masses of yellow pollen called pollinia.
If all petals and sepals are cut
from a flower, leaving only the column and stem, (the cylindrical rod
at the bottom of the left image), the main parts of the reproductive
system can be seen more clearly. The arrow-head shaped projection
is the viscidium, a sticky pad
to which the two pollinia are attached. This beak-like extension
is sometimes called the rostellum.
The bulbous yellow bump above the red “eye” is one of the two pollen
masses. If an investigating insect backs out of the flower, the
sharp point of the V-shaped viscidium is pulled away from the
column. Since it, and the attached pollinia are extremely
sticky, the entire cap may become attached to the back of the insect
and be carried away to another flower. Individual pollen grains
are not transported from flower to flower – it is the entire package
that is transferred.
The two images below show just what
is carried away by a visiting insect. Although it may look as
though the tweezers’ tips are holding the anther cap in position, this
is misleading. The “glue” on the viscidium and pollinia is so
strong that the cap is very firmly held in place without the second arm
of the tweezers being in contact. In fact, when the photographs
were finally taken, it was very difficult to dislodge the cap, even
with the aid of a tissue. (Someone should patent the glue!)
The microscope provides a closer
look at the two pollinia.
At a slightly higher magnification,
the filament holding one of the pollinia to the viscidium is visible.
The surface of the pollinia is very
bumpy as can be seen below.
An insect’s view looking straight
up at the underside of the column is shown below. The stigma, (the “cave” of shiny
material beneath the “beak”), is the female part of the flower. A
thin membrane beneath the anther cap prevents self-pollination.
After an insect strips off the
anther cap, two “teeth” called denticulae
are visible. These strip the pollen masses from the back of a
visiting insect, and perhaps hold the pollinia in contact with the
stigma’s surface to enable fertilization.
A closer view of the “platform”
beneath the column reveals its intricate shape.
Hook-like appendages at the very
tip of the flower’s lip can be seen below. It seems that these
structures serve no purpose, and are simply ornamental.
The buds of a phalaenopsis orchid
plant slowly increase in size over the blooming period. The
flowers bloom in sequence out towards the tip of the stem.
Several buds at various stages of development can be seen below.
Red “veins” on the surface of the
sepals which form the protective envelope for the developing flower,
can be seen in the second image below.
A sequence of four images shows the
opening of a bud. The photographs were taken over an eight hour
Branching red veins cover most of
the surface of both sepals and petals.
Within the throat of the tri-lobed
specialized petal, there are red spots as well as the veins that cover
all petals and sepals. The photomicrograph on the right shows the
structure of some of these cells. The darker nucleus is visible
At a much higher magnification, the
protuberances that exist at the edge of a petal are conspicuous.
Individual cells are also resolved
in the three photomicrographs below showing areas of the membrane
separating the pollinia from the stigma. It is this membrane that
prevents self-pollination in the phalaenopsis flower.
Unlike the seeds of most plants,
orchid seeds have no endosperm (stored food). In the wild, a
symbiotic relationship between the plant and a type of fungus provides
nutrition for the growing seeds. This relationship is called a mycorrhiza and derives from the term
“fungus root”. The mycorrhiza provides the sugars and
carbohydrates necessary for seed growth when the fungus invades the
developing embryo. The seed capsules that form may contain from 1
000 to 1 000 000 dust-like seeds.
Phalaenopsis orchids are the most
widely grown for the home environment. Their blooms are often
strikingly colourful and remarkably long lasting. Even someone
like myself, without even a hint of a “green thumb” can keep them alive
and blooming for a month or two!
The photographs in the article were
taken with an eight megapixel Sony CyberShot DSC-F 828 equipped with
achromatic close-up lenses (Nikon 5T, 6T, Sony VCL-M3358, and shorter
focal length achromat) used singly or in combination. The lenses screw
into the 58 mm filter threads of the camera lens. (These produce
a magnification of from 0.5X to 10X for a 4x6 inch image.) Still
higher magnifications were obtained by using a macro coupler (which has
two male threads) to attach a reversed 50 mm focal length f 1.4 Olympus
SLR lens to the F 828. (The magnification here is about 14X for a
4x6 inch image.) The photomicrographs were taken with a Leitz SM-Pol
microscope (using a dark ground condenser), and the Coolpix
Several web-sites providing
interesting information about orchids are listed below.
– From Wikipedia, the free encyclopedia
Orchid Page (http://www.orchidlady.com/index.html)
– Orchid (http://www.botany.com/orchidaceae.html)
Microscopy UK or their contributors.
Published in the
November 2007 edition of Micscape.
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