A Close-up View of a Bellflower Hybrid


A Close-up View of a Bellflower Hybrid

Campanula x hybrida 'Samantha'

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 protective sepals.

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 “bell-shaped”!

A side view of a flower reveals its fragile stalk, and the inverted dome-shaped ovary positioned below the sepals.

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 become entangled.

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.)

Campanula ‘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, vein structure.

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).

Photographic Equipment

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 images.

The photomicrographs were taken using a Leitz SM-Pol microscope (using a dark ground condenser), and the Coolpix 4500.

A Flower Garden of Macroscopic Delights

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.

 All comments to the author Brian Johnston are welcomed.

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