A Close-up View of a Lady's Slipper Orchid
Close-up View of a
Lady's Slipper Orchid
by Brian Johnston (Canada)
All Lady’s Slipper orchids belong
of the Orchidaceae.
differ from the rest of the orchids in that they possess two
instead of the usual one. Although in many orchids, one
forms a landing platform for insects, here it is transformed
elegant, and very distinctive pouch-shaped insect trap.
The Paphiopedilum genus was established
by Ernst Hugo Heinrich Pfitzer in 1886. Generated
one of the surnames of
Aphrodite, and pedilon
meaning a sandal, the genus translates to “Aphrodite’s sandal”.
in reference to the bulbous pouch which is the orchid’s
may not have a scent, but they more than make up for this
with their unique structure, and many diverse
Thousands of hybrids have been produced with a variety of
including white, yellow, maroon, red, pink and green.
petals often have hairs, spots, warts, and stripes which add to
flower’s visual interest – for both humans, and insects!
Many, but not all Paphiopedilums have
patterned leaves. The one shown below belongs to the
Slipper Orchid studied in this article.
Orchids normally have an outer
whorl composed of three sepals (modified leaves that protect the
flower’s bud stage), and an inner whorl of three petals. Paphiopedilums however, are
different. The distinctive banner-like structure at the
the flower is the dorsal sepal. The other two sepals are
and are fused together to form an apron-shaped structure that is
behind the pouch at the flower’s base.
Two of the three petals can be
as the purple-spotted wings that angle down from the flower’s
centre. The third petal is grotesquely transformed into
flower’s distinctive pouch.
A view from behind shows the synsepal – the apron-shaped
structure formed by the fused remaining two sepals. It
from the point where the flower’s stem-like ovary meets the
bloom. Notice that it too is white with green stripes.
The deformed, slipper-like
petal is called the labellum
or lip of the orchid,
we will see later, it plays an important part in the
The colour contrast between
dorsal sepal and the rest of the flower is striking.
The dorsal sepal is composed
translucent cells, and is quite different in substance from that
petals, which tend to be leathery. The light green “veins”
“ribs” are raised a considerable distance above the white tissue
rest of the sepal.
As the magnification is
the cellular structure of the sepal becomes easier to resolve.
All three of the flower’s
can be seen in the view from the back that follows. The
sepal points up, while the two lateral sepals are fused into the
synsepal, that points down.
The two slightly drooping
seen on the left and right in the image below, are grooved, and
by deep purple, wart-like spots.
A closer view of a petal
that it has many tiny hairs growing from both the upper, and
A petal’s surface is composed
cells which reflect light, and this results in it appearing
some lighting conditions.
Petal warts are very irregular
Before we look at the
strategy of the Paphiopedilum
orchid, a little terminology must be understood. Both the
flower’s male, and female reproductive organs are held at the
end of a
rod-like structure called the column
(or gynostemium), which
extension of the stem and ovary. Two fertile anthers are
to the column, one on either side. A curiously modified
anther, this one infertile, is located at the end of the
Looking somewhat like a shield, it is called the staminode. Also
the column, but hidden behind the staminode, is the flower’s
stigma. The relative positions of all of these
structures can be seen in the diagram that follows.
Since the anthers and stigma
hidden behind the staminode, a visiting insect cannot see
In other orchid species, the labellum provides a landing place
proximity to the reproductive parts - not here however.
searching for nectar, an insect may fall into the Paphiopedilum’s pouch, and
caught in the trap. Unfortunately for the insect, the
the pouch is lined with shiny, slippery cells – except in one
location! On the interior dorsal wall (the back of the
there exists a ladder made up of tiny hairs that point
Only here can the insect escape in the same way a wall climber
using the projections that are provided for that purpose.
the insect reaches the top of the labellum, it is very
positioned immediately below one or other of the anthers, and
Notice in the two images that
follow, how the sides at the back of the labellum curve inwards
produce a vertical tunnel that funnels the climbing insect into
The outer surfaces of the
labellum, (just below the staminode), are covered by reddish
appear particularly shiny.
Close examination of one of
surfaces reveals that it is coated by an appetizing (to insects)
liquid. Since there is no “foothold” for an insect to use
sipping the liquid, this increases the possibility of a fall
depths of the labellum – the carefully laid trap.
Before I begin to remove parts
the flower in order to provide a better view of the anthers and
take a look at the images below. The entire labellum will
removed, as well as both petals.
Here’s the result, shown in
front and side views. Only the dorsal sepal, and fused
sepals (synsepal) remain. The disk-shaped structure
beneath the staminode is the flower’s stigma, and its active
faces down in both images. The image on the right shows
the two ball-like anthers attached to the column.
Here is a better view of the
staminode, and the upper (non-active) surface of the stigma.
Note the red, nose-like
protuberance in the middle of the staminode. The entire
of the structure is coated with tiny, downward pointing hairs.
These hairs can be seen more
clearly below. Notice the interesting green pattern on the
Each anther is attached to the
column by a small horn or “hanger”. In Paphiopedilums, the pollen
in a waxy, fairly undefined mass with the consistency of mealy
beeswax. In the images below, this mass of pollen is
yellow, and a section of a sphere in shape. The paler
material attached to the outermost region of the pollen mass, is
the anther cap.
sticky, waxy cap is what gets stuck to the leg or body of an
it brushes against the structure. As the insect moves
carries the cap, and the attached pollen mass with it – perhaps
stigma of this flower, or perhaps to the stigma of a nearby
the same species. Self-fertilization would be the result
first possibility, and cross-fertilization the result of the
second. Of course, cross-fertilization is preferred for
long-term well-being of the species.
Between the plant’s stem, and
flower’s ovary, is a pair of small green leaflets. Notice
the ovary has a number of longitudinal grooves on its surface.
These grooves can be seen more
easily at higher magnifications.
The ovary is coated with a
multitude of tiny hairs.
In the wild, orchids often
particular insects that they attract to accomplish
Many use bees, while others have pollinator relationships with
butterflies, hummingbirds, flies, gnats and bats. Human
growers of course may use a toothpick to transfer the pollen
the flower’s stigma. Although not as exotic, the process
The low magnification, (to
macro-photographs were taken using a 13 megapixel Canon 5D full
DSLR, using a Canon EF 180 mm 1:3.5 L Macro lens.
An 8 megapixel Canon 20D DSLR,
equipped with a specialized high magnification (1x to 5x) Canon
lens, the MP-E 65 mm 1:2.8, was used to take the remainder of
Microscopy UK or their contributors.
Published in the
November 2011 edition of Micscape.
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