A Close-up View of a Bellflower Hybrid
View of a Bellflower Hybrid
Campanula x hybrida
by Brian Johnston (Canada)
The bellflowers are members of the Campanulaceae family, and take
their name from their bell-shaped flowers. (Campanula is Latin for “little
bell”.) Many members of the genus Campanula are truly bell-shaped,
but this hybrid is more ‘bowl’ than ‘bell’ shaped! It is also
unusual in that its flowers are upward-facing, rather than the normal
downward-facing habit of other members of the genus.
The plant is sold as groundcover,
and my specimen was about 20 centimetres in height. The flowers,
which open to a diameter of about 2 centimetres, produce an extremely
peasant scent. Above is an image showing a portion of the potted
plant. It should be noted that the literature suggests that the
flowers are a “rich blue” colour. Since the image gives a true
representation of the colour of my sample, I’ll leave it to the viewer
to decide whether the description is correct.
Near the centre of the image on the
left below, a deeply grooved, five lobed bud is visible. An even
earlier stage bud can be seen on the right.
New buds tend to be a shade of
yellow-green, and are surrounded by a whorl of pointed, darker green
sepals (modified leaves).
These bellflower buds have a
smaller ridge between each two prominent ridges.
The two images that follow show a
bud that is about to bloom. Notice in the lower half of the image
on the left, a bud so small that it is completely dwarfed by its
As a bud blooms, an opening first
appears at its tip. Notice that by this point the five sepals
have opened out into an almost planar star shape.
Immediately after blooming, flowers
are bowl-shaped, and have their deepest colouration around the top edge
of the corolla. The corolla has five, lobed segments which are
fused about half-way up from the base.
Many older blooms have a convex
upper surface. No one would describe such a flower as
A side view of a flower reveals its
fragile stalk, and the inverted dome-shaped ovary positioned below the
Higher magnification images of the
ovary reveal its unusual shape and colouration.
The outer surface of a flower’s
petal can be seen in the high magnification macrophotograph below.
Several of a petal’s smaller veins
can be seen in the two photomicrographs that follow. (Note that
the “auto-level” function was used to increase contrast, and therefore
the colours are not “true” in the images.)
At some locations on a petal’s
surface, the cells appear to be arranged in a jigsaw-like pattern.
The images that follow show the
bellflower’s reproductive structures. In the Campanula genus the number of
stamens is equal to the number of corolla lobes, in this case 5.
There is a three-lobed stigma, in which each lobe is curled into spiral
structure. At the pistil’s base there is a dome-shaped, white
nectary disk that holds the flower’s nectar.
This nectary disk can be seen
below. Note in the image on the right, that the disk is made up
of petals, and gaps between the petals are visible in the image.
It is through one of these gaps that the proboscis of an insect must
pass in order to obtain the sugary fluid.
Photomicrographs showing the
surface of an anther follow.
Two macrophotographs showing the
upper surface of a flower’s stigma lobes can be seen below. It is
this upper surface that is receptive to pollen. An unusual
situation is shown on the right where part of a lobe has malformed, and
Photomicrographs showing the active
surface follow. Note the hair-like protuberances that increase
its surface area, and help to acquire and retain pollen grains.
Occasionally, the three stigma
lobes uncurl to reveal their full length.
Four photomicrographs follow that
show the longer, and more pointed protuberances that this stigma
possesses. (The first image also shows a microscopically small
sucking insect at the tip of one of the lobes.)
‘Samantha’s’ leaves are heart-shaped.
Closer inspection shows that at the
tip of each lobe (or serration), there is a tiny, white, pointed
structure that resembles a tiny tooth. Note that a few white
hairs also grow from both the leaf’s edge, and surface.
A photomicrograph showing the
cellular structure of the upper surface of a leaf in shown on the right
below. Also note the pink spot resulting from damage of some kind
in the same image.
The tiny white tooth-like structure
mentioned earlier can be seen at higher magnification below.
Cells near the edge of the upper
surface of a leaf often possess a pink pigmentation.
A highly magnified image of a
section of the under-surface of a leaf shows its prominent, raised,
Photomicrographs showing the long
thin hairs that grow from the surface of veins can be seen below.
The Campanula genus contains many
well-known species, including Campanula
rotundifolia (Harebell – England and Bluebell – Scotland), and Campanula medium (Canterbury Bells).
The low magnification, (to 1:1),
macro-photographs were taken using a 13 megapixel Canon 5D full frame
DSLR, using a Canon EF 180 mm 1:3.5 L Macro lens.
An 10 megapixel Canon 40D DSLR,
equipped with a specialized high magnification (1x to 5x) Canon macro
lens, the MP-E 65 mm 1:2.8, was used to take the remainder of the
The photomicrographs were taken
using 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
A complete graphical index of all
of my crystal articles can be found here.
Microscopy UK or their contributors.
Published in the August
2011 edition of Micscape.
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