A Close-up View of the

"Pincushion Flower"

Scabiosa columbaria 'Butterfly Blue'

by Brian Johnston   (Canada)

The attractive blooms of this plant are supported by 30 to 40 centimetre long, delicate stems.  As a macro-photographer, I dislike such stems intensely!  Even indoors, the slightest air movement causes the flower being photographed to ‘bob’ up and down, left and right, and even backwards and forwards uncontrollably.  What causes the air to move?  Breathing, and focusing the lens are the worst offenders.  When I think of  the pincushion flower, it is the periods of breath-holding that come to mind most readily.  Unfortunately, long distance underwater swimming is not one of my interests, although I have certainly had enough training during the photography of this plant!

Pincushion flower’s common name derives from the fact that its long, needle-like pistils resemble pins sticking into a pincushion.  The plant studied here is a member of the teasel family (Dipsacaceae).  Some of its members belong to the genus Scabiosa, the name of which was chosen because the plants were believed to cure scabies.  (Other sources refer to the name being derived from the Latin scabiosa, which translates to “rough”.)  The species name columbaria means “dove-like”.

Scabiosa columbaria is native to the Mediterranean region of Europe, Western Asia and North Africa.  Alternative common names are Pigeon scabious, Small scabious and Dove pincushion.  Forty years ago, a grower for the Farplants organization, David Tristam, found an exceptional example in a garden in Ireland.  Cuttings from the plant were grown by Tristam for many years, and the cultivar was finally marketed as ‘Butterfly Blue’ in the late 1990’s.  The Perennial Plant Association awarded the title ‘Perennial Plant of the Year 2000’ to Scabiosa columbaria 'Butterfly Blue'.

Notice in the images that follow, that the stalk of one of the plant’s bud-stage flowerheads has grown longer, and that the sepals (modified leaves) have begun to open out into their final horizontal positions.

Long before the flower blooms, the stem has lengthened sufficiently to allow the flowerhead  to actively “search for light”.

An immature flowerhead is ringed by hairy, green, pointed sepals, and is composed of a number of light coloured flower buds with many bright red, hair-like threads sticking up between them.

The three images below show a botanical abnormality – conjoined stems, and conjoined immature flowerheads.  The stems are downy-soft due to their being covered with fine white hairs.

Side and back views of a ‘normal’ bud-stage flowerhead follow.

At higher magnifications, it can be seen that the surfaces of unopened, individual buds, are also covered with fine white hairs.  Each red projection is a pappus.  (Pappus hairs are attached to the seed of a plant, and may aid in its transfer to another location.)

As time passes, changes begin to occur in the flowerhead.  One change has to do with the shape of the unopened buds.  Those near the edge of the flowerhead become oval rather than circular, and they increase in size compared to those at the centre.  In addition, all of the unopened buds take on a purplish hue.

This colouration can be seen clearly in the two images below, showing outer, and inner portions of a flowerhead.

Finally, the buds begin to bloom.  Central ones open before those around the perimeter.

Shortly thereafter, the central flowers have opened sufficiently to allow the flat-topped, beige stigmas to be seen.  Notice that the petals have parallel sides (rather unusual), and a rounded tip.

Within a day, the flowerhead is completely in bloom.  I find it strange that the marketers of this cultivar would choose to name it ‘Butterfly Blue’.  To my eyes, all of the plant’s blooms are more purple than blue!  Perhaps ‘Butterfly Lilac Blue’ would be a better description.

The two images below show the ring of pointed sepals, of varying length, that cup the bottom of the flowerhead.

Higher magnifications reveal their hairy surfaces.

The flowerhead is composed of large-petaled ray flowers in an outer ring, and a central disk, containing much smaller-petaled disk flowers.  Ray flower petals are much deeper in colour than those of disk flowers.

As you can see below, a visiting insect would have a difficult time landing on the flowerhead’s central disk, without coming into contact with several pistils, (beige stigmas held aloft by purple styles). 

On the other hand, the relatively uncluttered surfaces of the outer ray petals might provide better, but less efficacious landing spots.

The image on the right below shows a low magnification photomicrograph of a petal.  Notice its scalloped edge.

At the top edge of a petal, tiny cylindrical cells can be seen against the black background.

The shape of these cells can be seen more clearly in the two images that follow, showing the central area of a petal.  Note that the strange colouration is produced as a side-effect of using Adobe Photoshop’s ‘Auto Levels’ function to increase contrast.

If all of the flowers are removed from one-half of a flowerhead, its structure becomes evident.  In the left image you can see individual tubular disk flowers, with their petals fused together at the bottom.  The image on the right shows the increase in size of these flowers as one moves towards the outer edge of the flowerhead.  The outermost ring consists of flowers that have larger, and more deeply coloured petals.

Earlier in the article I mentioned the numerous red hairs, (pappi), that grow out from between the flowers.  In the mature flowerhead, their short length prevents them from being visible to an ‘outside’ observer.

Although no mention has been made of a flower’s male reproductive organs, they do exist!  Stamens are hidden deep within the flower’s fused petal tube, and are therefore difficult to see.  Pollen covered anthers, (male pollen producing structures), are visible below in an outer ray flower (left image), and in a central disk flower (right image).

The shape of an anther can be seen in the photomicrographs that follow.  The one at right shows the anther’s supporting filament.

Several of the fine hairs that cover the outer surface of a disk flower petal can be seen in the higher magnification photomicrograph below.

A single disk flower is shown below, with its pistil protruding almost twice the length of the petal tube.  The photomicrograph at right shows its white stigma, and purple, supporting style.

Higher magnification reveals that the surface of the stigma is covered with circular, stubby protuberances.

The long cells that make up the surface structure of the style can be seen below.

Scabiosa columbaria has leaves of variable shape.  The one seen at left is lance-shaped, and finely divided into lobes of differing size and shape.  The leaf seen on the right has a typical ‘lance’ shape.  The upper surfaces of both are covered in fine hairs, with those at the edge being longer, and having a larger diameter.

On the left below, is a photomicrograph showing the cellular structure of the upper surface of a leaf.  The image at right shows a higher magnification photomicrograph of the hairs growing from a prominent vein on the leaf’s lower surface.

At first glance, the flowerheads of Scabiosa columbaria look as though they might belong to the aster family, (rather than the teasel family), because of their similar ray and disk flowers.  Irrespective of their family origins, they are certainly unique, and quite beautiful.

Photographic Equipment

All of 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 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.

Microscopy UK Front Page
Micscape Magazine
Article Library

© Microscopy UK or their contributors.

Published in the September 2008 edition of Micscape.
Please report any Web problems or offer general comments to the Micscape Editor.
Micscape is the on-line monthly magazine of the Microscopy UK web
site at Microscopy-UK  

© Onview.net Ltd, Microscopy-UK, and all contributors 1995 onwards. All rights reserved. Main site is at www.microscopy-uk.org.uk with full mirror at www.microscopy-uk.net .