A close-up view of a hellebore.

The family Ranunculaceae contains many genera, including the buttercups, anemones, and delphiniums. Surprisingly, the plant studied in this article also belongs to this family. Helleborus is a small genus, with plants that are markedly different from those of other members of the family. Its flowers do not have petals in the normal sense of the word. Instead its ‘petals’ are really sepals, (modified leaves), that have the shape of ‘petals’, but appear to be made of thicker, fleshier, leaf-like tissue. In fact, after the plant has bloomed, these sepals remain alive and heathy, essentially as long as the plant lives.

Botanists divide Hellebors into two distinct groups. Those that have visible, above-ground stems are referred to as caulescent, while those without above-ground stems are called acaulescent. As you can see in the image above, Helleborus Ivory Prince ‘Walhelivory’ does have stems, and so it is considered to be caulescent.

When flowers like the one below first bloom, the ring of showy sepals has a pinkish-beige colouration. This colour slowly fades to a more greenish hue after fertilization. Unlike normal petals, these sepals undergo a significant amount of photosynthetic activity, the amount of which increases after fertilization. The greenish hue is evidence of this photosynthetic increase.

Front and back views of a flower can be seen below. Notice the absence of greenish, protective bracts beneath the whorl of sepals. There are however, several narrow, spear-shaped leaflets on the stalk beneath the bloom.

The point of connection of flower to stalk can be seen below. Both the plant’s stems, and flowers’ stalks have a reddish hue. The stalks have a multitude of very tiny, light coloured protuberances over their surfaces.

The three stages in the life-cycle of a Hellebore flower are shown in the image that follows. Clockwise from bottom left, there is: the bud-stage, the blooming fertilization-ready flower, and the post-fertilization persistent stage.

Two examples of the bud-stage of the plant can be seen below.

The glossy, dark green leaves of this species are ovate in shape, and have a sharply serrated edge.

Evidence of the caulescent nature of this Hellebore can be seen in the image below showing an opening bud.

Looking into the open end of a bud, you can see the light coloured pistils, surrounded at their bases by many pale yellow, immature stamens. Around the stamens is a ring of light green tubes, which as we will see later, are the flower’s nectaries. (In the image at left, I have focused on the tops of these nectaries, while in the image on the right, I have focused on the tips of the stigmas.

Notice in the two images that follow, the strange modified leaflet structure. I have not seen this particular phenomenon in any other plant that I have studied.

Here is a mature Hellebore flower. At the base of the sepals, there is a ring of yellowish-green, tubular, or funnel-shaped nectaries. Some botanists refer to these as the actual, (highly modified), petals of the flower that have fused at their edges to form tubes. The flower’s insect attracting nectar is held at the base of these nectaries. Inside the nectary ring are many stamens composed of anthers, (male pollen producing organs), and their supporting filaments. At the centre of this group of stamens are the pistils (female reproductive organs).

When a bud first opens, the anthers are enclosed by yellowish-green anther-caps. Hellebore flowers are protogynus, which means that their stigmas are receptive before the stamens release pollen. This decreases the probability of the flower fertilizing itself, and encourages cross-fertilization. (In reality however, a Hellebore flower at a later stage can fertilize itself, and is referred to as being self-fertile.) In the images, the anthers and their filaments surround the swollen bases of the styles – (the ovaries which produce seeds).

At a slightly later stage, the anthers have taken on a yellowish-brown tinge, but they still have their anther-caps in place. The image on the left shows several of the flower’s nectaries. The third image provides another viewpoint. (The sepals have been removed from the flower in order to make it easier to differentiate the structures.)

Eventually, the anther caps darken, begin to disintegrate, and pollen starts to be released.

Higher magnification shows pollen grains clinging to anthers, filaments, and ovaries.

Here, the flower’s eight white stigmas (pollen accepting organs) are visible. Each is supported by a reddish-brown style.

These styles can be seen in the side-views shown below.

The next stage in the flower’s life-cycle is revealed below. Can you see what is missing? Yes, you’re right – the stamens have all shriveled and have fallen from the flower.

The images that follow show particularly well the shape of the flower’s nectaries.

Here finally, is the last stage in a flower’s transformation. By this time, the nectaries have fallen away from the fertilized flower, leaving only the (now greener) sepals, and the group of pistils. The flowers do not decay and fall from the plant as they do in many other species. These flowers will continue to look like this until the winter freeze kills the entire plant!

Hellebores have been cultivated, mainly in Europe, for hundreds of years. Although all contain harmful, poisonous alkaloids, they are sometimes used for ‘medical purposes’ in homeopathy and traditional medicines.

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 8 megapixel Canon 20D 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.

Reference

http://www.hellebores.org/

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A complete graphical index of all of my flower articles can be found here.

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