A Close-up View of Purple St. John's Wort

A Close-up View of

Purple St. John's Wort

Hypericum androsaemum

'Albury Purple'

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.

Hypericum 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 anther’s surface.

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 left image.

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.

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.

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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Published in the August 2010 edition of Micscape.
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