A close-up view of the 'bittersweet nightshade'.

This ubiquitous and attractive wildflower has many common names: Bittersweet Nightshade, European Bittersweet, Bitter Nightshade, Blue Nightshade, Fellenwort, and Woody Nightshade. Unfortunately, one common name, Deadly Nightshade, actually refers to an entirely different flower, Atropa belladonna. This latter plant is actually deadly when ingested, but it is seldom seen in North America. Bittersweet Nightshade is poisonous, but seldom causes death. (More about this later.)

The plant belongs to the family Solanaceae, often referred to as the Potato, or Nightshade family. Tomatoes, potatoes, peppers, eggplants, and tobacco plants are also members of this family.

In the area in which I live, Bittersweet Nightshade can be seen growing in moist locations both urban, and “wild”. My sample was found as a climbing vine, on an extremely old wooden fence, at the edge of an abandoned field.

As can be seen in the image above, the plant’s flowers have both a striking shape, and a quite beautiful intense purple, yellow, and green colouration.

Beginning in early May, masses of one centimetre diameter flowers appear against a backdrop of leaves.

New buds, surrounded by hairy, green leaflets, can be seen below.

Later, the entire bud becomes deep purple. Groups of buds are joined to branching stems by short stalks – which are also purple.

In the two images below, note the changes in shape and colour, as buds mature into fully blooming flowers.

As the five, pointed, purple petals of the flower open, they pass through an intermediate position where they are perpendicular to the column formed by the reproductive structures. Eventually however, they take up their final positions, in which they are folded back, away from the column. Both of these orientations can be seen in the two images that follow.

The structure and colouration of a Bittersweet Nightshade bloom is unusual, to say the least. Notice the flower’s deep purple centre, and the ring of bright, yellow-green spots at the petals’ bases. I suspect that these spots are “bright” in the ultraviolet reflected spectrum, and hence guide visiting insects to the flower’s “important parts”!

Transparent hairs fringe a petal’s edge, and to a lesser degree, cover a petal’s surface. It is the petal’s epithelial, or surface cells, that contain purple pigment. The hairs are colourless.

A vein-like structure on the surface of a petal can be seen in the two photomicrographs that follow. The image on the left is “true-colour”, while the one on the right has increased contrast due to the use of the “auto level” function in Adobe Photoshop.

Notice that the yellow-green spots mentioned earlier are visible on the underside of the petals as well.

Two photomicrographs showing the cellular structure, and colouration of the spots, can be seen below. The pattern produced is remarkable!

The dome-shaped yellow column at the flower’s centre is composed of the fused anthers (male pollen producing organs).

The photomicrographs below show close-up views of this column.

Solanum dulcamara pollen grains are ellipsoidal (egg-shaped).

Protruding out through the fused ring of anthers, is the flower’s pistil, which is composed of a pale green stigma, (female pollen accepting organ), and supporting pale green style. (Notice above and to the right of the flower, that the petals of a second, fertilized, flower have fallen off, and its domed green ovary (seed producing organ) has begun to increase in size.)

The image of a pistil’s tip follows. Notice that the style’s surface cells are rectangular (or brick-like) in shape, while those of the stigma are round (or spherical).

Flowers in a particular group are always in very different stages of development. Buds, mature flowers, and fruit of varying sizes can be seen in the examples below.

The first colour displayed by the fruit is green.

The green soon changes to yellow, then orange, and finally to a brilliant red.

Examples of the orange colouration can be seen below.

Bunches of berries are particularly striking, because there are different colours on display at the same time. The ripe berries of this plant are a favorite food of birds. (It has been determined that they are less toxic than unripe ones.)

The shape of the plant’s leaves is unusual. Notice the two basal lobes, or leaflets, at the base.

The underside of a leaf is covered with oval stomata, and their associated guard cells, that control gas transfer into, and out of, the structure.

Egg-shaped glands on short stalks grow profusely from the leaf’s veins.

Many plants of the genus Solanum contain glycoalkaloids (alkaloids + sugars). It is these chemical compounds that make the unripe berries, leaves, stems and roots poisonous. The toxicity decreases in the order listed.

Some jurisdictions consider Bittersweet Nightshade to be a pestilential weed. In my view it is an unusual, colourful, and quite beautiful wildflower.

Photographic Equipment

Most of the photographs in the article were taken with an eight megapixel Canon 20D DSLR and Canon EF 100 mm f 2.8 Macro lens. An eight megapixel Sony CyberShot DSC-F 828 equipped with achromatic close-up lenses (Canon 250D, Nikon 6T, and Sony VCL-M3358 used singly, or in combination), was used to take a few of the images.

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

References

Dickinson, Timothy, et al. 2004. The ROM Field Guide to Wildflowers of Ontario. Royal Ontario Museum & McClelland and Stewart Ltd, Toronto, Canada.

Thieret, John W. et al. National Audubon Society Field Guide to North American Wildflowers - Eastern Region. 2002. Alfred A. Knopf, Inc. (Chanticleer Press, Inc. New York)

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.

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