Close-up View of the Wildflower
by Brian Johnston (Canada)
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
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
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
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
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
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
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
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.
Dickinson, Timothy, et al. 2004. The ROM Field Guide to Wildflowers of
Ontario. Royal Ontario Museum & McClelland and Stewart Ltd,
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
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.
Microscopy UK or their contributors.
Published in the August
2008 edition of Micscape.
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