A Close-up View of the



Anemone coronaria

(De Caen Group)

by Brian Johnston   (Canada)

If anemone blooms were yellow in colour, their general structure might lead one to believe that they were extra large buttercups.  It’s not surprising then, to find that both flowers are members of the same family – Ranunculaceae.  Both possess the raised, central mound of tightly packed pistils, the crown-like rings of stamens around the central mound, (hence the species name coronaria or crown), and a relatively small number of large rounded petals.

Most of the anemone plants available for the garden, or as cut flowers, are cultivars produced by horticulturalists.  Anemone cultivars are divided into two groups, those with single flowers called the “De Caen Group”, and those with semi-double flowers called the “St. Brigid Group”.  Members of the De Caen Group have flowers with from 5 to 8 petals (or tepals as they should be called).  (Many flowers have a ring of leaflets (or sepals), below the ring of petals.  If the sepals and petals are indistinguishable, they are given the collective name tepals.)

Greek mythology suggests that the anemone flower grew from the blood of Aphrodite’s slain lover, Adonis.  The name anemone, roughly translated from the Greek “anemos”, means wind.  This may derive from Pliny’s comment that anemone blossoms are opened by the wind.  Alternative names for the plant are windflower, or poppy anemone.

The image above, and the two that follow, show the most common De Caen anemone colours, purple and red.  Since the central mound of pistils in the red flower was unsymmetrical, I decided to photograph the purple one for the article.  (Note that the macro-images were taken over a period of two years.  For the second group of photographs, I deliberately chose another purple bloom to match those from the earlier group.)

First, let’s look at the general structural details of an anemone flower.  There are six tepals with rounded tips surrounding a central mound of pistils.  The “crown” of stamens surrounds this central mound.

In this particular bloom, the central mound is yellow, and is covered by what look like purple hairs.  Notice that most of the anthers are deep purple, while a few are a light beige colour.

The central mound of pistils has a striking appearance due to the colour contrast between the base material and the purple hairs.

Each anther is divided into two halves, and is held in position by a deep purple filament.  There is considerable variation in the colour of the anthers.

A much higher magnification shows the pointed tips of the purple structures on the mound of pistils. (More about this later.)

Now let’s look at a flower in more detail.  Notice in the bloom shown below, that the inner rings of anthers are much lighter in colour than the anthers in outer rings.  Also notice the out-of-focus yellow edge on the top-most tepals in the image.

In fact, the yellow edge is due to the large number of light coloured hairs that grow out from the back surface of each tepal.

Under the microscope, the underside of a tepal clearly shows veins, and the epithelial (surface) cellular structure.  Notice at the centre of the third image, that a stoma, and its associated guard cells are clearly visible.  (These structures control gas transfer into and out of the tepal.)

The front, or upper surface of a tepal is covered with many strangely shaped protuberances.

Immature anthers (pollen producing organs) are beige in colour, and have practically no pollen on their surfaces.

At the magnification shown in the image at left below, the rough surfaces of mature, deep purple anthers become visible.  Notice in the image at right, that the anthers transition from beige, through light purple to their final deep purple colour.

A still higher magnification reveals that only one surface of an anther has a coating of pollen grains.  The other surface has a strange, ridged banding pattern that can be observed most clearly in the top left corner of the left image.

Under the microscope, one can see the two arc-shaped sections of a mature anther, and the thinner, lighter coloured tissue that connects them.

The cellular structure of the supporting filament is shown below.

The middle section of the anther contains cells with a variety of colours.  It is interesting to find what appear to be stoma and guard cells in an anther!  Usually one sees these in leaves.

Cells that produce the strange ridged, banding pattern mentioned earlier, can be seen in the photomicrographs below.

Immature anthers do not display the ridged pattern, although they are similar in shape and size to the mature variety.  This is probably due to the fact that the surface is not as reflective as in the mature anther, and the reflective highlights aid in their visualization.

Evidence for this hypothesis can be seen in the photomicrograph of an immature anther.  The same cells that produce the ridges are present!

Pollen grains, and several stoma and guard cells are visible here as well.  Notice in the image at right, that the purple colouration that signals the onset of anther maturity is beginning to appear in the surface cells.

The mound of tissue that is covered by many hundreds of pistils is shown at left.  On the right is a single pistil (dissected from the mound), that is composed of the tiny stigma (pollen accepting organ), the supporting style, and the bulbous ovary (seed producing organ).

The cellular structure of the style is remarkably similar to that of the filament seen earlier.

If the top of one of the ovaries in the image at left is magnified, large hairs can be seen to cover the surface.

Anemone leaves have many segments, and are toothed at the edges.

One of these teeth can be seen in the photomicrographs below.  Notice the long hairs that grow from the leaf’s edge.

Hairs are also present on the surface of the leaf (lower left corner of image at left).  Stoma and guard cells are visible in the higher magnification image at right.

The purplish-blue colour of individual pollen grains is visible in the photomicrograph at left, and in the crop of the image at right.  Notice the very interesting surface pattern that can be seen clearly on several grains.

Brightly coloured anemone flowers are a visual feast for the eyes.  I hope that the “macro” and “micro” views shown in the article have provided even more evidence of their natural beauty.

Photographic Equipment

Most 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.

A few photographs were taken with an eight megapixel Sony CyberShot DSC-F 828 equipped with achromatic close-up lenses (Canon 250D, 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.

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

 All comments to the author Brian Johnston are welcomed.

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