A Close-up View of a

Persian Buttercup Hybrid

Ranunculus asiaticus

(Bloomingdale Series)

by Brian Johnston   (Canada)

Unlike the common wildflower buttercup, which is uniformly yellow in colour, this dwarf variety of Ranunculus asiaticus has multiple layers of striking, multicoloured, tissue-paper thin petals.  As you will see in this article, many quite different colour variations grow in the same container.

The Bloomingdale series of Persian buttercups, (alternatively Turban Buttercup or Persian Crowfoot), were derived from a species growing in South-western Asia and South-eastern Europe in the early 1980’s.  The plants grow to a maximum height of about 25 centimetres, and the blooms on my plant had diameter of about 8 centimetres.

The first image in the article, and the one below show a particularly fine example.

However, not all examples are as fine as the one above.  Here is a smaller, less symmetrical bloom.

Developing buds are completely protected by a ring of five, pointed sepals.

Closer examination reveals that the sepals’ outer surfaces are completely covered by very fine, soft hairs.

As the bud increases in size it separates the sepals, but it is interesting to note that they still remain in contact with the top of the bud.  At this stage, the final colour of the flower is nowhere to be seen.

Eventually, at the point where the bud’s size is great enough to separate the sepal tips, the petals’ final colour combination becomes evident.  When a blooming plant is described as being beautiful, it is usually understood that it is the flowers that are so described.  It has been my experience that in many cases the appellation belongs to the buds as well! 

Soon the sepals separate completely from the flower’s mass of tightly packed petals and provide an elegant base for the opening flower.

While still tightly packed into a ball shape, the random red and white patterns on the petals’ surfaces can certainly be considered ‘eye-candy’!

Closer views of both the top and side of an opening flower reveal strange floral landscapes.

Notice that a sepal has a single prominent vein running its full length.  There are much less evident veins on either side of the main one.

As the thin, fragile layers of petals open out and separate from one another, they push the sepals back out of the way.  Eventually, in most views the sepals are not visible at all.  In this flower the central disk with its bright green colour, contrasts strikingly with the red, pink and white lower petals.

Let’s now take a closer look at the petals in the transition area between the green upper, and pink lower areas.

I have already mentioned the hairiness of the flower’s sepals.  In the image below there are hints that the edges of petals have hairs as well.

Confirmation of this observation comes from examining the following photomicrographs.  The edge of one of the light green sections of a petal was photographed with the microscope and it is apparent, particularly in the second image, that the hairs are completely transparent!

Notice the tip of the petal seen in the centre of the image below.  Both green and pink pigmentations are present.

If this petal is examined under the microscope, the pigmented cells themselves can be seen.  The second image shows a higher magnification view of cells in the pink section, and the third image provides a view of a detail in the white area.

While photographing the plant, I noticed that there was no evidence of reproductive structures in any of the flowers.  Since this seemed unlikely, I began pulling away petals in the region of the flower where the stamens and pistil are usually found.  Still seeing nothing, I continued to peel tiny petals from the tiny green onion-like structure that can be seen in the second and third images below.  Eventually, there was nothing left.  The mystery will be solved in the next section of the article!

Although the plant’s label at the garden centre read ‘Bloomingdale Series’, I suspect that the correct label was ‘Bloomingdale Mix’ since the flowers had such dramatically different colourations.  The images that follow show another variation, a flower with no green centre, and mostly white petals with narrow dark red fringes along the edges.

Views from the back reveal that the base petals are not white, but black on their undersides.

Closer views reveal that hidden beneath the central whorl of petals, there is indeed a small green disk.

Strangely, another flower with a similar colouration has completely white base petals rather than the pink of the earlier example.

When looking through the DSLR viewfinder to take the picture shown below, I thought that my eyes might be deceiving me.  Hidden between the whorl of central petals there appeared to be stamens.  At last I had found a flower with reproductive structures!

After peeling away the overhanging ring of petals, both stamens and pistil were revealed.

Closer views reveal that of necessity, the structures are more tightly packed, and arranged in a more random pattern than those of most other flowers.

The flower’s many anthers look a little like over-ripe bananas.  The are mostly yellow with areas of dark blue, and have a groove along their length.  No pollen grains are visible.  At the centre of the group is a prominent domed stigma with a rough surface.

The two images below show the deep longitudinal groove on an anther’s surface.

Many of the anthers have strange curvatures.

The anther’s supporting filament is usually hidden in the overall ‘mess’ but here is one that is viewable.

Photomicrographs taken of the surfaces of several anthers can be seen below.

The anthers visible in the previous images had not yet begun to release pollen – a process referred to as dehiscing.  I was forced to peel away part of an anther’s protective membrane in order to obtain images of Persian Buttercup pollen grains.  They appear to be spherical, and almost featureless.

Buttercups tend to have large numbers of pistils in a mound at the flower’s centre.  This plant is no exception.  Even in a macro-photograph it is possible to see the many fine, colourless, hair-like stigmas in the mound.

If you look closely at the photomicrographs below that show a portion of the mound, you can see the pointed tips of the stigmas, the supporting styles, and at the bases of the styles, the ovoid ovaries.

Near the base of the mound of pistils, the stigmas and styles are shorter, and it is easier to distinguish the swollen ovaries.

By pulling away some of the crowded pistils, it is easier to see surface details of the ovary.

Ranunculus leaves are described as rounded, and deeply three-lobed.

Photomicrographs showing a leaf’s upper surface can be seen below.

Similar views showing the lower surface of a leaf follow.  Note the oval stomata and guard cells that control gas transfer into, and out of, a leaf’s interior.

Finally, here are two views of one of the plant’s stems.  Note its intense hairiness.

The striking bi-coloured or multi-coloured flowers of Persian Buttercup hybrids certainly make them ideal ornamental plants in gardens or planters.

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.

A 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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