A Close-up View of Purple St. John's Wort
Close-up View of
Purple St. John's Wort
by Brian Johnston (Canada)
The approximately four hundred species
belonging to the genus Hypericum
are members of the Clusiaceae
family, and most are referred to as St.
John’s Worts. Alternatively called Hypericums, they
are sometimes referred to as Tutsans
or Rose of Sharon’s. The
common name Tutsan is derived from the French words “tout” meaning all,
and “sain” meaning healthy. Historically, many of these species
had medicinal uses.
androsaemum ‘Albury Purple’, the cultivar studied in this
article, has plum-purple highlighted, green leaves, and bright
yellow-orange flowers. Its species name, androsaemum translates to “human
blood”, and refers to the plant’s resinous sap.
The first image in the article, and
the one below, both show the blooming plant at its most colourful in
the early summer period. As you can see, each flower is ringed at
its base by a number of small leaflets (or bracts).
Although the oval, purple-green
leaves seem at first glance to be opaque, in bright light they transmit
some light. The image on the left below shows this phenomenon
which accentuates the leaf’s complex vein structure. On the right
is a higher magnification image showing the more three-dimensional back
surface of the same leaf.
At an earlier stage, before the
plant’s buds have opened, the leaves are almost completely green in
colour, and the aforementioned bracts are pale greenish-white (left
image). As time passes the bracts become light green (right
image). The buds themselves are yellow, with orange-red stripes.
Immediately before blooming, these
buds are bright red in colour, and their surrounding bracts are mottled
with deep purple patterns.
The view below shows the tip of one
of the plant’s stems with its many bud stalks, each tipped with a ring
of darkening bracts.
As the flower’s petals open, its
many stamens, and prominent egg-shaped ovary are revealed.
The blooming flower is
approximately two centimetres in diameter, and has five, rounded,
rose-like petals. Surrounding the base of the central ovary are
many filaments supporting pollen producing anthers.
Higher magnification reveals the
coating of white pollen grains that covers most, (but not all), of an
Under the microscope, details on
the lower (left), and upper (right) surfaces of the anther can be seen
more easily. Notice the light brown supporting filament in the
The cellular structure of this
filament can be seen in the higher magnification photomicrograph below.
A flower’s three-lobed pistil
emerges from the top of its three-compartmented ovary.
Notice in the image on the right
below that a number of pollen grains adhere to the rough surface of the
in-focus stigma lobe.
Under the microscope, bright red,
stubby, hair-like protuberances are visible. They increase the
stigma’s surface area, and thus increase the possibility of the capture
and retention of pollen grains.
Common St. John’s Wort, (Hypericum perforatum), is a
wildflower with similar flower structure. Unlike the wildflower
however, Hypericum androsaemum
‘Albury Purple’ does not possess the tiny black spots on petals
and leaves that are one of the distinguishing characteristics of the perforatum species. Not
surprisingly, the cultivar is considerably more visually striking than
its wildflower cousin.
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
The photomicrographs were taken
using a Leitz SM-Pol microscope (using a dark ground condenser), and
the Coolpix 4500.
A Flower Garden of
A complete graphical index of all
of my flower articles can be found here.
The Colourful World of
A complete graphical index of all
of my crystal articles can be found here.
Microscopy UK or their contributors.
Published in the August
2010 edition of Micscape.
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